Add nullability annotations to core/spring-boot-docker-compose

See gh-46587

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/ConnectionPorts.java

@@ -18,6 +18,8 @@ package org.springframework.boot.docker.compose.core;
 
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Provides access to the ports that can be used to connect to a {@link RunningService}.
  *
@@ -52,6 +54,6 @@ public interface ConnectionPorts {
 	 * all host ports
 	 * @return a list of all host ports using the given protocol
 	 */
-	List<Integer> getAll(String protocol);
+	List<Integer> getAll(@Nullable String protocol);
 
 }

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DefaultConnectionPorts.java

@@ -22,6 +22,8 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.docker.compose.core.DockerCliInspectResponse.Config;
 import org.springframework.boot.docker.compose.core.DockerCliInspectResponse.HostConfig;
 import org.springframework.boot.docker.compose.core.DockerCliInspectResponse.HostPort;
@@ -57,7 +59,7 @@ class DefaultConnectionPorts implements ConnectionPorts {
 		return (config != null) && "host".equals(config.networkMode());
 	}
 
-	private Map<ContainerPort, Integer> buildMappingsForNetworkSettings(NetworkSettings networkSettings) {
+	private Map<ContainerPort, Integer> buildMappingsForNetworkSettings(@Nullable NetworkSettings networkSettings) {
 		if (networkSettings == null || CollectionUtils.isEmpty(networkSettings.ports())) {
 			return Collections.emptyMap();
 		}
@@ -73,7 +75,7 @@ class DefaultConnectionPorts implements ConnectionPorts {
 		return Collections.unmodifiableMap(mappings);
 	}
 
-	private boolean isIpV4(HostPort hostPort) {
+	private boolean isIpV4(@Nullable HostPort hostPort) {
 		String ip = (hostPort != null) ? hostPort.hostIp() : null;
 		return !StringUtils.hasLength(ip) || ip.contains(".");
 	}
@@ -108,7 +110,7 @@ class DefaultConnectionPorts implements ConnectionPorts {
 	}
 
 	@Override
-	public List<Integer> getAll(String protocol) {
+	public List<Integer> getAll(@Nullable String protocol) {
 		List<Integer> hostPorts = new ArrayList<>();
 		this.mappings.forEach((containerPort, hostPort) -> {
 			if (protocol == null || protocol.equalsIgnoreCase(containerPort.protocol())) {

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DefaultDockerCompose.java

@@ -25,6 +25,8 @@ import java.util.Map.Entry;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.logging.LogLevel;
 import org.springframework.util.Assert;
 
@@ -41,7 +43,7 @@ class DefaultDockerCompose implements DockerCompose {
 
 	private final DockerHost hostname;
 
-	DefaultDockerCompose(DockerCli cli, String host) {
+	DefaultDockerCompose(DockerCli cli, @Nullable String host) {
 		this.cli = cli;
 		this.hostname = DockerHost.get(host, () -> cli.run(new DockerCliCommand.Context()));
 	}
@@ -114,7 +116,8 @@ class DefaultDockerCompose implements DockerCompose {
 		return inspectResponses.stream().collect(Collectors.toMap(DockerCliInspectResponse::id, Function.identity()));
 	}
 
-	private DockerCliInspectResponse inspectContainer(String id, Map<String, DockerCliInspectResponse> inspected) {
+	private @Nullable DockerCliInspectResponse inspectContainer(String id,
+			Map<String, DockerCliInspectResponse> inspected) {
 		DockerCliInspectResponse inspect = inspected.get(id);
 		if (inspect != null) {
 			return inspect;

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DefaultRunningService.java

@@ -19,6 +19,8 @@ package org.springframework.boot.docker.compose.core;
 import java.util.Collections;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.origin.Origin;
 import org.springframework.boot.origin.OriginProvider;
 
@@ -45,10 +47,10 @@ class DefaultRunningService implements RunningService, OriginProvider {
 
 	private final DockerEnv env;
 
-	private final DockerComposeFile composeFile;
+	private final @Nullable DockerComposeFile composeFile;
 
-	DefaultRunningService(DockerHost host, DockerComposeFile composeFile, DockerCliComposePsResponse composePsResponse,
+	DefaultRunningService(DockerHost host, @Nullable DockerComposeFile composeFile,
-			DockerCliInspectResponse inspectResponse) {
+			DockerCliComposePsResponse composePsResponse, DockerCliInspectResponse inspectResponse) {
 		this.origin = new DockerComposeOrigin(composeFile, composePsResponse.name());
 		this.name = composePsResponse.name();
 		this.image = ImageReference
@@ -101,7 +103,7 @@ class DefaultRunningService implements RunningService, OriginProvider {
 	}
 
 	@Override
-	public DockerComposeFile composeFile() {
+	public @Nullable DockerComposeFile composeFile() {
 		return this.composeFile;
 	}
 

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerCli.java

@@ -27,6 +27,7 @@ import java.util.function.Consumer;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.docker.compose.core.DockerCliCommand.ComposeVersion;
 import org.springframework.boot.docker.compose.core.DockerCliCommand.Type;
@@ -60,7 +61,7 @@ class DockerCli {
 	 * @param workingDirectory the working directory or {@code null}
 	 * @param dockerComposeOptions the Docker Compose options to use or {@code null}.
 	 */
-	DockerCli(File workingDirectory, DockerComposeOptions dockerComposeOptions) {
+	DockerCli(@Nullable File workingDirectory, @Nullable DockerComposeOptions dockerComposeOptions) {
 		this.processRunner = new ProcessRunner(workingDirectory);
 		this.dockerCommands = dockerCommandsCache.computeIfAbsent(workingDirectory,
 				(key) -> new DockerCommands(this.processRunner));
@@ -82,7 +83,7 @@ class DockerCli {
 		return dockerCommand.deserialize(json);
 	}
 
-	private Consumer<String> createOutputConsumer(LogLevel logLevel) {
+	private @Nullable Consumer<String> createOutputConsumer(@Nullable LogLevel logLevel) {
 		if (logLevel == null || logLevel == LogLevel.OFF) {
 			return null;
 		}
@@ -123,7 +124,7 @@ class DockerCli {
 	 * Return the {@link DockerComposeFile} being used by this CLI instance.
 	 * @return the Docker Compose file
 	 */
-	DockerComposeFile getDockerComposeFile() {
+	@Nullable DockerComposeFile getDockerComposeFile() {
 		return this.dockerComposeOptions.composeFile();
 	}
 
@@ -205,11 +206,14 @@ class DockerCli {
 	 * @param activeProfiles the profiles to activate
 	 * @param arguments the arguments to pass to Docker Compose
 	 */
-	record DockerComposeOptions(DockerComposeFile composeFile, Set<String> activeProfiles, List<String> arguments) {
+	record DockerComposeOptions(@Nullable DockerComposeFile composeFile, Set<String> activeProfiles,
+			List<String> arguments) {
 
-		DockerComposeOptions {
+		DockerComposeOptions(@Nullable DockerComposeFile composeFile, @Nullable Set<String> activeProfiles,
-			activeProfiles = (activeProfiles != null) ? activeProfiles : Collections.emptySet();
+				@Nullable List<String> arguments) {
-			arguments = (arguments != null) ? arguments : Collections.emptyList();
+			this.composeFile = composeFile;
+			this.activeProfiles = (activeProfiles != null) ? activeProfiles : Collections.emptySet();
+			this.arguments = (arguments != null) ? arguments : Collections.emptyList();
 		}
 
 		static DockerComposeOptions none() {

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerCliCommand.java

@@ -78,8 +78,8 @@ abstract sealed class DockerCliCommand<R> {
 
 	@SuppressWarnings("unchecked")
 	R deserialize(String json) {
-		if (this.responseType == Void.class) {
+		if (this.responseType == None.class) {
-			return null;
+			return (R) None.INSTANCE;
 		}
 		return (R) ((!this.listResponse) ? DockerJson.deserialize(json, this.responseType)
 				: DockerJson.deserializeToList(json, this.responseType));
@@ -175,10 +175,10 @@ abstract sealed class DockerCliCommand<R> {
 	/**
 	 * The {@code docker compose up} command.
 	 */
-	static final class ComposeUp extends DockerCliCommand<Void> {
+	static final class ComposeUp extends DockerCliCommand<None> {
 
 		ComposeUp(LogLevel logLevel, List<String> arguments) {
-			super(Type.DOCKER_COMPOSE, logLevel, Void.class, false, getCommand(arguments));
+			super(Type.DOCKER_COMPOSE, logLevel, None.class, false, getCommand(arguments));
 		}
 
 		private static String[] getCommand(List<String> arguments) {
@@ -196,10 +196,10 @@ abstract sealed class DockerCliCommand<R> {
 	/**
 	 * The {@code docker compose down} command.
 	 */
-	static final class ComposeDown extends DockerCliCommand<Void> {
+	static final class ComposeDown extends DockerCliCommand<None> {
 
 		ComposeDown(Duration timeout, List<String> arguments) {
-			super(Type.DOCKER_COMPOSE, Void.class, false, getCommand(timeout, arguments));
+			super(Type.DOCKER_COMPOSE, None.class, false, getCommand(timeout, arguments));
 		}
 
 		private static String[] getCommand(Duration timeout, List<String> arguments) {
@@ -216,10 +216,10 @@ abstract sealed class DockerCliCommand<R> {
 	/**
 	 * The {@code docker compose start} command.
 	 */
-	static final class ComposeStart extends DockerCliCommand<Void> {
+	static final class ComposeStart extends DockerCliCommand<None> {
 
 		ComposeStart(LogLevel logLevel, List<String> arguments) {
-			super(Type.DOCKER_COMPOSE, logLevel, Void.class, false, getCommand(arguments));
+			super(Type.DOCKER_COMPOSE, logLevel, None.class, false, getCommand(arguments));
 		}
 
 		private static String[] getCommand(List<String> arguments) {
@@ -234,10 +234,10 @@ abstract sealed class DockerCliCommand<R> {
 	/**
 	 * The {@code docker compose stop} command.
 	 */
-	static final class ComposeStop extends DockerCliCommand<Void> {
+	static final class ComposeStop extends DockerCliCommand<None> {
 
 		ComposeStop(Duration timeout, List<String> arguments) {
-			super(Type.DOCKER_COMPOSE, Void.class, false, getCommand(timeout, arguments));
+			super(Type.DOCKER_COMPOSE, None.class, false, getCommand(timeout, arguments));
 		}
 
 		private static String[] getCommand(Duration timeout, List<String> arguments) {
@@ -268,6 +268,15 @@ abstract sealed class DockerCliCommand<R> {
 
 	}
 
+	static final class None {
+
+		public static final None INSTANCE = new None();
+
+		private None() {
+		}
+
+	}
+
 	/**
 	 * Docker compose version.
 	 *

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerCliComposePsResponse.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.docker.compose.core;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Response from {@link DockerCliCommand.ComposePs docker compose ps}.
  *
@@ -27,6 +29,6 @@ package org.springframework.boot.docker.compose.core;
  * @author Andy Wilkinson
  * @author Phillip Webb
  */
-record DockerCliComposePsResponse(String id, String name, String image, String state) {
+record DockerCliComposePsResponse(String id, String name, @Nullable String image, String state) {
 
 }

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerCliInspectResponse.java

@@ -19,6 +19,8 @@ package org.springframework.boot.docker.compose.core;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Response from {@link DockerCliCommand.Inspect docker inspect}.
  *
@@ -31,7 +33,8 @@ import java.util.Map;
  * @author Phillip Webb
  */
 record DockerCliInspectResponse(String id, DockerCliInspectResponse.Config config,
-		DockerCliInspectResponse.NetworkSettings networkSettings, DockerCliInspectResponse.HostConfig hostConfig) {
+		DockerCliInspectResponse.NetworkSettings networkSettings,
+		DockerCliInspectResponse.@Nullable HostConfig hostConfig) {
 
 	/**
 	 * Configuration for the container that is portable between hosts.

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerCompose.java

@@ -21,6 +21,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.docker.compose.core.DockerCli.DockerComposeOptions;
 import org.springframework.boot.logging.LogLevel;
 
@@ -126,7 +128,7 @@ public interface DockerCompose {
 	 * @param activeProfiles a set of the profiles that should be activated
 	 * @return a {@link DockerCompose} instance
 	 */
-	static DockerCompose get(DockerComposeFile file, String hostname, Set<String> activeProfiles) {
+	static DockerCompose get(DockerComposeFile file, @Nullable String hostname, Set<String> activeProfiles) {
 		return get(file, hostname, activeProfiles, Collections.emptyList());
 	}
 
@@ -140,7 +142,7 @@ public interface DockerCompose {
 	 * @return a {@link DockerCompose} instance
 	 * @since 3.4.0
 	 */
-	static DockerCompose get(DockerComposeFile file, String hostname, Set<String> activeProfiles,
+	static DockerCompose get(DockerComposeFile file, @Nullable String hostname, Set<String> activeProfiles,
 			List<String> arguments) {
 		DockerCli cli = new DockerCli(null, new DockerComposeOptions(file, activeProfiles, arguments));
 		return new DefaultDockerCompose(cli, hostname);

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerComposeFile.java

@@ -26,6 +26,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -107,7 +109,7 @@ public final class DockerComposeFile {
 	 * current directory
 	 * @return the located file or {@code null} if no Docker Compose file can be found
 	 */
-	public static DockerComposeFile find(File workingDirectory) {
+	public static @Nullable DockerComposeFile find(@Nullable File workingDirectory) {
 		File base = (workingDirectory != null) ? workingDirectory : new File(".");
 		if (!base.exists()) {
 			return null;

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerComposeOrigin.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.docker.compose.core;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.origin.Origin;
 
 /**
@@ -27,7 +29,7 @@ import org.springframework.boot.origin.Origin;
  * @author Andy Wilkinson
  * @since 3.1.0
  */
-public record DockerComposeOrigin(DockerComposeFile composeFile, String serviceName) implements Origin {
+public record DockerComposeOrigin(@Nullable DockerComposeFile composeFile, String serviceName) implements Origin {
 
 	@Override
 	public String toString() {

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerEnv.java

@@ -21,6 +21,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.CollectionUtils;
 
 /**
@@ -69,7 +71,7 @@ class DockerEnv {
 		return this.map;
 	}
 
-	private record Entry(String key, String value) {
+	private record Entry(String key, @Nullable String value) {
 
 	}
 

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerHost.java

@@ -21,6 +21,8 @@ import java.util.List;
 import java.util.function.Function;
 import java.util.function.Supplier;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.StringUtils;
 
 /**
@@ -69,7 +71,7 @@ final class DockerHost {
 	 * {@link DockerCliContextResponse}
 	 * @return a new docker host instance
 	 */
-	static DockerHost get(String host, Supplier<List<DockerCliContextResponse>> contextsSupplier) {
+	static DockerHost get(@Nullable String host, Supplier<List<DockerCliContextResponse>> contextsSupplier) {
 		return get(host, System::getenv, contextsSupplier);
 	}
 
@@ -81,7 +83,7 @@ final class DockerHost {
 	 * {@link DockerCliContextResponse}
 	 * @return a new docker host instance
 	 */
-	static DockerHost get(String host, Function<String, String> systemEnv,
+	static DockerHost get(@Nullable String host, Function<String, String> systemEnv,
 			Supplier<List<DockerCliContextResponse>> contextsSupplier) {
 		host = (StringUtils.hasText(host)) ? host : fromServicesHostEnv(systemEnv);
 		host = (StringUtils.hasText(host)) ? host : fromDockerHostEnv(systemEnv);
@@ -94,24 +96,24 @@ final class DockerHost {
 		return systemEnv.apply("SERVICES_HOST");
 	}
 
-	private static String fromDockerHostEnv(Function<String, String> systemEnv) {
+	private static @Nullable String fromDockerHostEnv(Function<String, String> systemEnv) {
 		return fromEndpoint(systemEnv.apply("DOCKER_HOST"));
 	}
 
-	private static String fromCurrentContext(Supplier<List<DockerCliContextResponse>> contextsSupplier) {
+	private static @Nullable String fromCurrentContext(Supplier<List<DockerCliContextResponse>> contextsSupplier) {
 		DockerCliContextResponse current = getCurrentContext(contextsSupplier.get());
 		return (current != null) ? fromEndpoint(current.dockerEndpoint()) : null;
 	}
 
-	private static DockerCliContextResponse getCurrentContext(List<DockerCliContextResponse> candidates) {
+	private static @Nullable DockerCliContextResponse getCurrentContext(List<DockerCliContextResponse> candidates) {
 		return candidates.stream().filter(DockerCliContextResponse::current).findFirst().orElse(null);
 	}
 
-	private static String fromEndpoint(String endpoint) {
+	private static @Nullable String fromEndpoint(@Nullable String endpoint) {
 		return (StringUtils.hasLength(endpoint)) ? fromUri(URI.create(endpoint)) : null;
 	}
 
-	private static String fromUri(URI uri) {
+	private static @Nullable String fromUri(URI uri) {
 		try {
 			return switch (uri.getScheme()) {
 				case "http", "https", "tcp" -> uri.getHost();

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/ImageName.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.docker.compose.core;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -38,7 +40,7 @@ class ImageName {
 
 	private final String string;
 
-	ImageName(String domain, String path) {
+	ImageName(@Nullable String domain, String path) {
 		Assert.hasText(path, "'path' must not be empty");
 		this.domain = getDomainOrDefault(domain);
 		this.name = getNameWithDefaultPath(this.domain, path);
@@ -90,7 +92,7 @@ class ImageName {
 		return this.string;
 	}
 
-	private String getDomainOrDefault(String domain) {
+	private String getDomainOrDefault(@Nullable String domain) {
 		if (domain == null || LEGACY_DOMAIN.equals(domain)) {
 			return DEFAULT_DOMAIN;
 		}
@@ -104,7 +106,7 @@ class ImageName {
 		return name;
 	}
 
-	static String parseDomain(String value) {
+	static @Nullable String parseDomain(String value) {
 		int firstSlash = value.indexOf('/');
 		String candidate = (firstSlash != -1) ? value.substring(0, firstSlash) : null;
 		if (candidate != null && Regex.DOMAIN.matcher(candidate).matches()) {

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/ImageReference.java

@@ -18,6 +18,8 @@ package org.springframework.boot.docker.compose.core;
 
 import java.util.regex.Matcher;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
@@ -32,13 +34,13 @@ public final class ImageReference {
 
 	private final ImageName name;
 
-	private final String tag;
+	private final @Nullable String tag;
 
-	private final String digest;
+	private final @Nullable String digest;
 
 	private final String string;
 
-	private ImageReference(ImageName name, String tag, String digest) {
+	private ImageReference(ImageName name, @Nullable String tag, @Nullable String digest) {
 		Assert.notNull(name, "'name' must not be null");
 		this.name = name;
 		this.tag = tag;
@@ -68,7 +70,7 @@ public final class ImageReference {
 	 * Return the tag from the reference or {@code null}.
 	 * @return the referenced tag
 	 */
-	public String getTag() {
+	public @Nullable String getTag() {
 		return this.tag;
 	}
 
@@ -76,7 +78,7 @@ public final class ImageReference {
 	 * Return the digest from the reference or {@code null}.
 	 * @return the referenced digest
 	 */
-	public String getDigest() {
+	public @Nullable String getDigest() {
 		return this.digest;
 	}
 
@@ -111,7 +113,7 @@ public final class ImageReference {
 		return this.string;
 	}
 
-	private String buildString(String name, String tag, String digest) {
+	private String buildString(String name, @Nullable String tag, @Nullable String digest) {
 		StringBuilder string = new StringBuilder(name);
 		if (tag != null) {
 			string.append(":").append(tag);

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/ProcessExitException.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.docker.compose.core;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Exception thrown by {@link ProcessRunner} when the process exits with a non-zero code.
  *
@@ -37,7 +39,7 @@ class ProcessExitException extends RuntimeException {
 		this(exitCode, command, stdOut, stdErr, null);
 	}
 
-	ProcessExitException(int exitCode, String[] command, String stdOut, String stdErr, Throwable cause) {
+	ProcessExitException(int exitCode, String[] command, String stdOut, String stdErr, @Nullable Throwable cause) {
 		super(buildMessage(exitCode, command, stdOut, stdErr), cause);
 		this.exitCode = exitCode;
 		this.command = command;

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/ProcessRunner.java

@@ -29,6 +29,7 @@ import java.util.function.Consumer;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.log.LogMessage;
 
@@ -47,7 +48,7 @@ class ProcessRunner {
 
 	private static final Log logger = LogFactory.getLog(ProcessRunner.class);
 
-	private final File workingDirectory;
+	private final @Nullable File workingDirectory;
 
 	/**
 	 * Create a new {@link ProcessRunner} instance.
@@ -60,7 +61,7 @@ class ProcessRunner {
 	 * Create a new {@link ProcessRunner} instance.
 	 * @param workingDirectory the working directory for the process
 	 */
-	ProcessRunner(File workingDirectory) {
+	ProcessRunner(@Nullable File workingDirectory) {
 		this.workingDirectory = workingDirectory;
 	}
 
@@ -83,7 +84,7 @@ class ProcessRunner {
 	 * @return the output of the command
 	 * @throws ProcessExitException if execution failed
 	 */
-	String run(Consumer<String> outputConsumer, String... command) {
+	String run(@Nullable Consumer<String> outputConsumer, String... command) {
 		logger.trace(LogMessage.of(() -> "Running '%s'".formatted(String.join(" ", command))));
 		Process process = startProcess(command);
 		ReaderThread stdOutReader = new ReaderThread(process.getInputStream(), "stdout", outputConsumer);
@@ -133,13 +134,13 @@ class ProcessRunner {
 
 		private final InputStream source;
 
-		private final Consumer<String> outputConsumer;
+		private final @Nullable Consumer<String> outputConsumer;
 
 		private final StringBuilder output = new StringBuilder();
 
 		private final CountDownLatch latch = new CountDownLatch(1);
 
-		ReaderThread(InputStream source, String name, Consumer<String> outputConsumer) {
+		ReaderThread(InputStream source, String name, @Nullable Consumer<String> outputConsumer) {
 			this.source = source;
 			this.outputConsumer = outputConsumer;
 			setName("OutputReader-" + name);
@@ -174,7 +175,7 @@ class ProcessRunner {
 				return this.output.toString();
 			}
 			catch (InterruptedException ex) {
-				return null;
+				return "";
 			}
 		}
 

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/RunningService.java

@@ -18,6 +18,8 @@ package org.springframework.boot.docker.compose.core;
 
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Provides details of a running Docker Compose service.
  *
@@ -69,7 +71,7 @@ public interface RunningService {
 	 * @return the Docker Compose file
 	 * @since 3.5.0
 	 */
-	default DockerComposeFile composeFile() {
+	default @Nullable DockerComposeFile composeFile() {
 		return null;
 	}
 

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Core interfaces and classes for working with Docker Compose.
  */
+@NullMarked
 package org.springframework.boot.docker.compose.core;
+
+import org.jspecify.annotations.NullMarked;

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/lifecycle/DockerComposeLifecycleManager.java

@@ -23,6 +23,7 @@ import java.util.Set;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.aot.AotDetector;
 import org.springframework.boot.SpringApplicationShutdownHandlers;
@@ -57,11 +58,11 @@ class DockerComposeLifecycleManager {
 
 	private static final String IGNORE_LABEL = "org.springframework.boot.ignore";
 
-	private final File workingDirectory;
+	private final @Nullable File workingDirectory;
 
 	private final ApplicationContext applicationContext;
 
-	private final ClassLoader classLoader;
+	private final @Nullable ClassLoader classLoader;
 
 	private final SpringApplicationShutdownHandlers shutdownHandlers;
 
@@ -80,10 +81,10 @@ class DockerComposeLifecycleManager {
 				new DockerComposeSkipCheck(), null);
 	}
 
-	DockerComposeLifecycleManager(File workingDirectory, ApplicationContext applicationContext, Binder binder,
+	DockerComposeLifecycleManager(@Nullable File workingDirectory, ApplicationContext applicationContext, Binder binder,
 			SpringApplicationShutdownHandlers shutdownHandlers, DockerComposeProperties properties,
 			Set<ApplicationListener<?>> eventListeners, DockerComposeSkipCheck skipCheck,
-			ServiceReadinessChecks serviceReadinessChecks) {
+			@Nullable ServiceReadinessChecks serviceReadinessChecks) {
 		this.workingDirectory = workingDirectory;
 		this.applicationContext = applicationContext;
 		this.classLoader = applicationContext.getClassLoader();

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/lifecycle/DockerComposeProperties.java

@@ -23,6 +23,8 @@ import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.boot.docker.compose.core.RunningService;
@@ -64,7 +66,7 @@ public class DockerComposeProperties {
 	/**
 	 * Hostname or IP of the machine where the docker containers are started.
 	 */
-	private String host;
+	private @Nullable String host;
 
 	/**
 	 * Start configuration.
@@ -109,11 +111,11 @@ public class DockerComposeProperties {
 		this.lifecycleManagement = lifecycleManagement;
 	}
 
-	public String getHost() {
+	public @Nullable String getHost() {
 		return this.host;
 	}
 
-	public void setHost(String host) {
+	public void setHost(@Nullable String host) {
 		this.host = host;
 	}
 

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/lifecycle/DockerComposeSkipCheck.java

@@ -20,6 +20,8 @@ import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.SpringApplicationAotProcessor;
 import org.springframework.util.ClassUtils;
 
@@ -44,7 +46,7 @@ class DockerComposeSkipCheck {
 		SKIPPED_STACK_ELEMENTS = Collections.unmodifiableSet(skipped);
 	}
 
-	boolean shouldSkip(ClassLoader classLoader, DockerComposeProperties.Skip properties) {
+	boolean shouldSkip(@Nullable ClassLoader classLoader, DockerComposeProperties.Skip properties) {
 		if (properties.isInTests() && hasAtLeastOneRequiredClass(classLoader)) {
 			Thread thread = Thread.currentThread();
 			for (StackTraceElement element : thread.getStackTrace()) {
@@ -56,7 +58,7 @@ class DockerComposeSkipCheck {
 		return false;
 	}
 
-	private boolean hasAtLeastOneRequiredClass(ClassLoader classLoader) {
+	private boolean hasAtLeastOneRequiredClass(@Nullable ClassLoader classLoader) {
 		for (String requiredClass : REQUIRED_CLASSES) {
 			if (ClassUtils.isPresent(requiredClass, classLoader)) {
 				return true;

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/lifecycle/ServiceNotReadyException.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.docker.compose.lifecycle;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.docker.compose.core.RunningService;
 
 /**
@@ -33,7 +35,7 @@ class ServiceNotReadyException extends RuntimeException {
 		this(service, message, null);
 	}
 
-	ServiceNotReadyException(RunningService service, String message, Throwable cause) {
+	ServiceNotReadyException(RunningService service, String message, @Nullable Throwable cause) {
 		super(message, cause);
 		this.service = service;
 	}

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/lifecycle/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Lifecycle management for Docker Compose with the context of a Spring application.
  */
+@NullMarked
 package org.springframework.boot.docker.compose.lifecycle;
+
+import org.jspecify.annotations.NullMarked;

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/service/connection/DockerComposeConnectionDetailsFactory.java

@@ -21,6 +21,8 @@ import java.util.Arrays;
 import java.util.Set;
 import java.util.function.Predicate;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.autoconfigure.service.connection.ConnectionDetails;
 import org.springframework.boot.autoconfigure.service.connection.ConnectionDetailsFactory;
 import org.springframework.boot.docker.compose.core.DockerComposeFile;
@@ -92,7 +94,7 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 	}
 
 	@Override
-	public final D getConnectionDetails(DockerComposeConnectionSource source) {
+	public final @Nullable D getConnectionDetails(DockerComposeConnectionSource source) {
 		return (!accept(source)) ? null : getDockerComposeConnectionDetails(source);
 	}
 
@@ -112,7 +114,7 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 	 * @param source the source
 	 * @return the service connection or {@code null}.
 	 */
-	protected abstract D getDockerComposeConnectionDetails(DockerComposeConnectionSource source);
+	protected abstract @Nullable D getDockerComposeConnectionDetails(DockerComposeConnectionSource source);
 
 	/**
 	 * Convenient base class for {@link ConnectionDetails} results that are backed by a
@@ -120,9 +122,9 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 	 */
 	protected static class DockerComposeConnectionDetails implements ConnectionDetails, OriginProvider {
 
-		private final Origin origin;
+		private final @Nullable Origin origin;
 
-		private volatile SslBundle sslBundle;
+		private volatile @Nullable SslBundle sslBundle;
 
 		/**
 		 * Create a new {@link DockerComposeConnectionDetails} instance.
@@ -134,11 +136,11 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 		}
 
 		@Override
-		public Origin getOrigin() {
+		public @Nullable Origin getOrigin() {
 			return this.origin;
 		}
 
-		protected SslBundle getSslBundle(RunningService service) {
+		protected @Nullable SslBundle getSslBundle(RunningService service) {
 			if (this.sslBundle != null) {
 				return this.sslBundle;
 			}
@@ -155,7 +157,7 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 			return sslBundle;
 		}
 
-		private SslBundle getJksSslBundle(RunningService service) {
+		private @Nullable SslBundle getJksSslBundle(RunningService service) {
 			JksSslStoreDetails keyStoreDetails = getJksSslStoreDetails(service, "keystore");
 			JksSslStoreDetails trustStoreDetails = getJksSslStoreDetails(service, "truststore");
 			if (keyStoreDetails == null && trustStoreDetails == null) {
@@ -173,13 +175,13 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 					options, protocol);
 		}
 
-		private ResourceLoader getResourceLoader(Path workingDirectory) {
+		private ResourceLoader getResourceLoader(@Nullable Path workingDirectory) {
 			ClassLoader classLoader = ApplicationResourceLoader.get().getClassLoader();
 			return ApplicationResourceLoader.get(classLoader,
 					SpringFactoriesLoader.forDefaultResourceLocation(classLoader), workingDirectory);
 		}
 
-		private JksSslStoreDetails getJksSslStoreDetails(RunningService service, String storeType) {
+		private @Nullable JksSslStoreDetails getJksSslStoreDetails(RunningService service, String storeType) {
 			String type = service.labels().get("org.springframework.boot.sslbundle.jks.%s.type".formatted(storeType));
 			String provider = service.labels()
 				.get("org.springframework.boot.sslbundle.jks.%s.provider".formatted(storeType));
@@ -193,7 +195,7 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 			return new JksSslStoreDetails(type, provider, location, password);
 		}
 
-		private Path getWorkingDirectory(RunningService runningService) {
+		private @Nullable Path getWorkingDirectory(RunningService runningService) {
 			DockerComposeFile composeFile = runningService.composeFile();
 			if (composeFile == null || CollectionUtils.isEmpty(composeFile.getFiles())) {
 				return Path.of(".");
@@ -201,7 +203,7 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 			return composeFile.getFiles().get(0).toPath().getParent();
 		}
 
-		private SslOptions createSslOptions(String ciphers, String enabledProtocols) {
+		private SslOptions createSslOptions(@Nullable String ciphers, @Nullable String enabledProtocols) {
 			Set<String> ciphersSet = null;
 			if (StringUtils.hasLength(ciphers)) {
 				ciphersSet = StringUtils.commaDelimitedListToSet(ciphers);
@@ -213,7 +215,7 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 			return SslOptions.of(ciphersSet, enabledProtocolsSet);
 		}
 
-		private SslBundle getPemSslBundle(RunningService service) {
+		private @Nullable SslBundle getPemSslBundle(RunningService service) {
 			PemSslStoreDetails keyStoreDetails = getPemSslStoreDetails(service, "keystore");
 			PemSslStoreDetails trustStoreDetails = getPemSslStoreDetails(service, "truststore");
 			if (keyStoreDetails == null && trustStoreDetails == null) {
@@ -231,7 +233,7 @@ public abstract class DockerComposeConnectionDetailsFactory<D extends Connection
 					PemSslStore.load(trustStoreDetails, resourceLoader)), key, options, protocol);
 		}
 
-		private PemSslStoreDetails getPemSslStoreDetails(RunningService service, String storeType) {
+		private @Nullable PemSslStoreDetails getPemSslStoreDetails(RunningService service, String storeType) {
 			String type = service.labels().get("org.springframework.boot.sslbundle.pem.%s.type".formatted(storeType));
 			String certificate = service.labels()
 				.get("org.springframework.boot.sslbundle.pem.%s.certificate".formatted(storeType));

core/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/service/connection/package-info.java

@@ -17,4 +17,7 @@
 /**
  * Service connection support for Docker Compose.
  */
+@NullMarked
 package org.springframework.boot.docker.compose.service.connection;
+
+import org.jspecify.annotations.NullMarked;

core/spring-boot-docker-compose/src/test/java/org/springframework/boot/docker/compose/core/DockerCliCommandTests.java

@@ -22,6 +22,7 @@ import java.util.List;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.docker.compose.core.DockerCliCommand.ComposeVersion;
+import org.springframework.boot.docker.compose.core.DockerCliCommand.None;
 import org.springframework.boot.logging.LogLevel;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -85,7 +86,7 @@ class DockerCliCommandTests {
 		assertThat(command.getLogLevel()).isEqualTo(LogLevel.INFO);
 		assertThat(command.getCommand(COMPOSE_VERSION)).containsExactly("up", "--no-color", "--detach", "--wait",
 				"--renew-anon-volumes");
-		assertThat(command.deserialize("[]")).isNull();
+		assertThat(command.deserialize("[]")).isSameAs(None.INSTANCE);
 	}
 
 	@Test
@@ -94,7 +95,7 @@ class DockerCliCommandTests {
 				List.of("--remove-orphans"));
 		assertThat(command.getType()).isEqualTo(DockerCliCommand.Type.DOCKER_COMPOSE);
 		assertThat(command.getCommand(COMPOSE_VERSION)).containsExactly("down", "--timeout", "1", "--remove-orphans");
-		assertThat(command.deserialize("[]")).isNull();
+		assertThat(command.deserialize("[]")).isSameAs(None.INSTANCE);
 	}
 
 	@Test
@@ -103,7 +104,7 @@ class DockerCliCommandTests {
 		assertThat(command.getType()).isEqualTo(DockerCliCommand.Type.DOCKER_COMPOSE);
 		assertThat(command.getLogLevel()).isEqualTo(LogLevel.INFO);
 		assertThat(command.getCommand(COMPOSE_VERSION)).containsExactly("start", "--dry-run");
-		assertThat(command.deserialize("[]")).isNull();
+		assertThat(command.deserialize("[]")).isSameAs(None.INSTANCE);
 	}
 
 	@Test
@@ -111,7 +112,7 @@ class DockerCliCommandTests {
 		DockerCliCommand<?> command = new DockerCliCommand.ComposeStop(Duration.ofSeconds(1), List.of("--dry-run"));
 		assertThat(command.getType()).isEqualTo(DockerCliCommand.Type.DOCKER_COMPOSE);
 		assertThat(command.getCommand(COMPOSE_VERSION)).containsExactly("stop", "--timeout", "1", "--dry-run");
-		assertThat(command.deserialize("[]")).isNull();
+		assertThat(command.deserialize("[]")).isSameAs(None.INSTANCE);
 	}
 
 	@Test