Repackage Javapoet in org.springframework.javapoet

This commit repackages the Javapoet library into spring-core so that it
can be used by the AOT engine without requiring a specific version.

Closes gh-27828

spring-core/spring-core.gradle

@@ -4,14 +4,17 @@ description = "Spring Core"
 
 apply plugin: "kotlin"
 
-// spring-core includes asm and repackages cglib, inlining both into the spring-core jar.
-// cglib itself depends on asm and is therefore further transformed by the ShadowJar task to
-// depend on org.springframework.asm; this avoids including two different copies of asm.
+// spring-core includes asm, javapoet and repackages cglib, inlining all into the
+// spring-core jar. cglib itself depends on asm and is therefore further transformed by
+// the ShadowJar task to depend on org.springframework.asm; this avoids including two
+// different copies of asm.
 def cglibVersion = "3.3.0"
+def javapoetVersion = "1.13.0"
 def objenesisVersion = "3.2"
 
 configurations {
 	cglib
+	javapoet
 	objenesis
 }
 
@@ -23,6 +26,13 @@ task cglibRepackJar(type: ShadowJar) {
 	relocate 'org.objectweb.asm', 'org.springframework.asm'
 }
 
+task javapoetRepackJar(type: ShadowJar) {
+	archiveBaseName.set('spring-javapoet-repack')
+	archiveVersion.set(javapoetVersion)
+	configurations = [project.configurations.javapoet]
+	relocate 'com.squareup.javapoet', 'org.springframework.javapoet'
+}
+
 task objenesisRepackJar(type: ShadowJar) {
 	archiveBaseName.set('spring-objenesis-repack')
 	archiveVersion.set(objenesisVersion)
@@ -32,8 +42,10 @@ task objenesisRepackJar(type: ShadowJar) {
 
 dependencies {
 	cglib("cglib:cglib:${cglibVersion}@jar")
+	javapoet("com.squareup:javapoet:${javapoetVersion}@jar")
 	objenesis("org.objenesis:objenesis:${objenesisVersion}@jar")
 	api(files(cglibRepackJar))
+	api(files(javapoetRepackJar))
 	api(files(objenesisRepackJar))
 	api(project(":spring-jcl"))
 	compileOnly("io.projectreactor.tools:blockhound")
@@ -83,6 +95,11 @@ jar {
 		exclude "org/springframework/cglib/proxy/MethodProxy*.class"
 	}
 
+	dependsOn javapoetRepackJar
+	from(zipTree(javapoetRepackJar.archivePath)) {
+		include "org/springframework/javapoet/**"
+	}
+
 	dependsOn objenesisRepackJar
 	from(zipTree(objenesisRepackJar.archivePath)) {
 		include "org/springframework/objenesis/**"

spring-core/src/main/java/org/springframework/javapoet/package-info.java

@@ -0,0 +1,6 @@
+/**
+ * Spring's repackaging of
+ * <a href="https://github.com/square/javapoet">JavaPoet</a>
+ * (with Spring-specific utilities; for internal use only).
+ */
+package org.springframework.javapoet;

src/docs/dist/license.txt

@@ -255,6 +255,14 @@ CGLIB 3.3 is licensed under the Apache License, version 2.0, the text of which
 is included above.
 
 
+>>> JavaPoet 1.13.0 (com.squareup:javapoet:1.13.0):
+
+Per the LICENSE file in the CGLIB JAR distribution downloaded from
+https://github.com/square/javapoet/archive/refs/tags/javapoet-1.13.0.zip,
+JavaPoet 1.13.0 is licensed under the Apache License, version 2.0, the text of
+which is included above.
+
+
 >>> Objenesis 3.1 (org.objenesis:objenesis:3.1):
 
 Per the LICENSE file in the Objenesis ZIP distribution downloaded from