Clarify behavior for generics support in BeanUtils.copyProperties()
Since Spring Framework 5.3, BeanUtils.copyProperties() honors generics in the source and target property types (see gh-24187); however, this refinement of the contract was not properly documented prior to this commit. In addition, the refinement can be a breaking change for users who were relying on the previous unreliable behavior. This commit therefore clarifies the behavior for generics support in BeanUtils.copyProperties() and introduces a table of example matches and mismatches when generics are involved. Closes gh-27259
This commit is contained in:
Sam Brannen
parent
d9c22e657f
commit
887389d341
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@ -1,5 +1,5 @@
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/*
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* Copyright 2002-2021 the original author or authors.
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* Copyright 2002-2022 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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@ -691,7 +691,25 @@ public abstract class BeanUtils {
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* from each other, as long as the properties match. Any bean properties that the
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* source bean exposes but the target bean does not will silently be ignored.
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* <p>This is just a convenience method. For more complex transfer needs,
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* consider using a full BeanWrapper.
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* consider using a full {@link BeanWrapper}.
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* <p>As of Spring Framework 5.3, this method honors generic type information
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* when matching properties in the source and target objects.
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* <p>The following table provides a non-exhaustive set of examples of source
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* and target property types that can be copied as well as source and target
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* property types that cannot be copied.
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* <table border="1">
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* <tr><th>source property type</th><th>target property type</th><th>copy supported</th></tr>
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* <tr><td>{@code Integer}</td><td>{@code Integer}</td><td>yes</td></tr>
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* <tr><td>{@code Integer}</td><td>{@code Number}</td><td>yes</td></tr>
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* <tr><td>{@code List<Integer>}</td><td>{@code List<Integer>}</td><td>yes</td></tr>
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* <tr><td>{@code List<?>}</td><td>{@code List<?>}</td><td>yes</td></tr>
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* <tr><td>{@code List<Integer>}</td><td>{@code List<?>}</td><td>yes</td></tr>
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* <tr><td>{@code List<Integer>}</td><td>{@code List<? extends Number>}</td><td>yes</td></tr>
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* <tr><td>{@code String}</td><td>{@code Integer}</td><td>no</td></tr>
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* <tr><td>{@code Number}</td><td>{@code Integer}</td><td>no</td></tr>
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* <tr><td>{@code List<Integer>}</td><td>{@code List<Long>}</td><td>no</td></tr>
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* <tr><td>{@code List<Integer>}</td><td>{@code List<Number>}</td><td>no</td></tr>
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* </table>
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* @param source the source bean
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* @param target the target bean
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* @throws BeansException if the copying failed
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@ -708,7 +726,10 @@ public abstract class BeanUtils {
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* from each other, as long as the properties match. Any bean properties that the
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* source bean exposes but the target bean does not will silently be ignored.
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* <p>This is just a convenience method. For more complex transfer needs,
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* consider using a full BeanWrapper.
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* consider using a full {@link BeanWrapper}.
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* <p>As of Spring Framework 5.3, this method honors generic type information
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* when matching properties in the source and target objects. See the
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* documentation for {@link #copyProperties(Object, Object)} for details.
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* @param source the source bean
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* @param target the target bean
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* @param editable the class (or interface) to restrict property setting to
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@ -726,7 +747,10 @@ public abstract class BeanUtils {
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* from each other, as long as the properties match. Any bean properties that the
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* source bean exposes but the target bean does not will silently be ignored.
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* <p>This is just a convenience method. For more complex transfer needs,
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* consider using a full BeanWrapper.
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* consider using a full {@link BeanWrapper}.
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* <p>As of Spring Framework 5.3, this method honors generic type information
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* when matching properties in the source and target objects. See the
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* documentation for {@link #copyProperties(Object, Object)} for details.
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* @param source the source bean
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* @param target the target bean
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* @param ignoreProperties array of property names to ignore
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@ -743,7 +767,8 @@ public abstract class BeanUtils {
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* from each other, as long as the properties match. Any bean properties that the
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* source bean exposes but the target bean does not will silently be ignored.
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* <p>As of Spring Framework 5.3, this method honors generic type information
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* when matching properties in the source and target objects.
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* when matching properties in the source and target objects. See the
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* documentation for {@link #copyProperties(Object, Object)} for details.
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* @param source the source bean
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* @param target the target bean
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* @param editable the class (or interface) to restrict property setting to
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@ -1,5 +1,5 @@
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/*
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* Copyright 2002-2021 the original author or authors.
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* Copyright 2002-2022 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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@ -203,8 +203,25 @@ class BeanUtilsTests {
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assertThat(tb2.getTouchy().equals(tb.getTouchy())).as("Touchy copied").isTrue();
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}
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/**
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* {@code Integer} can be copied to {@code Number}.
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*/
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@Test
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void copyPropertiesHonorsGenericTypeMatches() {
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void copyPropertiesFromSubTypeToSuperType() {
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IntegerHolder integerHolder = new IntegerHolder();
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integerHolder.setNumber(42);
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NumberHolder numberHolder = new NumberHolder();
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BeanUtils.copyProperties(integerHolder, numberHolder);
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assertThat(integerHolder.getNumber()).isEqualTo(42);
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assertThat(numberHolder.getNumber()).isEqualTo(42);
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}
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/**
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* {@code List<Integer>} can be copied to {@code List<Integer>}.
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*/
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@Test
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void copyPropertiesHonorsGenericTypeMatchesFromIntegerToInteger() {
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IntegerListHolder1 integerListHolder1 = new IntegerListHolder1();
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integerListHolder1.getList().add(42);
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IntegerListHolder2 integerListHolder2 = new IntegerListHolder2();
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@ -214,6 +231,68 @@ class BeanUtilsTests {
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assertThat(integerListHolder2.getList()).containsOnly(42);
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}
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/**
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* {@code List<?>} can be copied to {@code List<?>}.
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*/
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@Test
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void copyPropertiesHonorsGenericTypeMatchesFromWildcardToWildcard() {
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List<?> list = Arrays.asList("foo", 42);
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WildcardListHolder1 wildcardListHolder1 = new WildcardListHolder1();
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wildcardListHolder1.setList(list);
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WildcardListHolder2 wildcardListHolder2 = new WildcardListHolder2();
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assertThat(wildcardListHolder2.getList()).isEmpty();
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BeanUtils.copyProperties(wildcardListHolder1, wildcardListHolder2);
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assertThat(wildcardListHolder1.getList()).isEqualTo(list);
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assertThat(wildcardListHolder2.getList()).isEqualTo(list);
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}
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/**
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* {@code List<Integer>} can be copied to {@code List<?>}.
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*/
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@Test
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void copyPropertiesHonorsGenericTypeMatchesFromIntegerToWildcard() {
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IntegerListHolder1 integerListHolder1 = new IntegerListHolder1();
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integerListHolder1.getList().add(42);
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WildcardListHolder2 wildcardListHolder2 = new WildcardListHolder2();
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BeanUtils.copyProperties(integerListHolder1, wildcardListHolder2);
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assertThat(integerListHolder1.getList()).containsOnly(42);
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assertThat(wildcardListHolder2.getList()).isEqualTo(Arrays.asList(42));
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}
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/**
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* {@code List<Integer>} can be copied to {@code List<? extends Number>}.
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*/
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@Test
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void copyPropertiesHonorsGenericTypeMatchesForUpperBoundedWildcard() {
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IntegerListHolder1 integerListHolder1 = new IntegerListHolder1();
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integerListHolder1.getList().add(42);
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NumberUpperBoundedWildcardListHolder numberListHolder = new NumberUpperBoundedWildcardListHolder();
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BeanUtils.copyProperties(integerListHolder1, numberListHolder);
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assertThat(integerListHolder1.getList()).containsOnly(42);
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assertThat(numberListHolder.getList()).hasSize(1);
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assertThat(numberListHolder.getList().contains(Integer.valueOf(42))).isTrue();
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}
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/**
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* {@code Number} can NOT be copied to {@code Integer}.
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*/
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@Test
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void copyPropertiesDoesNotCopyeFromSuperTypeToSubType() {
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NumberHolder numberHolder = new NumberHolder();
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numberHolder.setNumber(Integer.valueOf(42));
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IntegerHolder integerHolder = new IntegerHolder();
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BeanUtils.copyProperties(numberHolder, integerHolder);
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assertThat(numberHolder.getNumber()).isEqualTo(42);
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assertThat(integerHolder.getNumber()).isNull();
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}
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/**
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* {@code List<Integer>} can NOT be copied to {@code List<Long>}.
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*/
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@Test
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void copyPropertiesDoesNotHonorGenericTypeMismatches() {
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IntegerListHolder1 integerListHolder = new IntegerListHolder1();
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@ -225,6 +304,20 @@ class BeanUtilsTests {
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assertThat(longListHolder.getList()).isEmpty();
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}
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/**
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* {@code List<Integer>} can NOT be copied to {@code List<Number>}.
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*/
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@Test
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void copyPropertiesDoesNotHonorGenericTypeMismatchesFromSubTypeToSuperType() {
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IntegerListHolder1 integerListHolder = new IntegerListHolder1();
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integerListHolder.getList().add(42);
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NumberListHolder numberListHolder = new NumberListHolder();
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BeanUtils.copyProperties(integerListHolder, numberListHolder);
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assertThat(integerListHolder.getList()).containsOnly(42);
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assertThat(numberListHolder.getList()).isEmpty();
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}
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@Test // gh-26531
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void copyPropertiesIgnoresGenericsIfSourceOrTargetHasUnresolvableGenerics() throws Exception {
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Order original = new Order("test", Arrays.asList("foo", "bar"));
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@ -413,6 +506,90 @@ class BeanUtilsTests {
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}
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@SuppressWarnings("unused")
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private static class NumberHolder {
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private Number number;
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public Number getNumber() {
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return number;
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}
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public void setNumber(Number number) {
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this.number = number;
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}
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}
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@SuppressWarnings("unused")
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private static class IntegerHolder {
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private Integer number;
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public Integer getNumber() {
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return number;
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}
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public void setNumber(Integer number) {
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this.number = number;
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}
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}
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@SuppressWarnings("unused")
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private static class WildcardListHolder1 {
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private List<?> list = new ArrayList<>();
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public List<?> getList() {
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return list;
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}
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public void setList(List<?> list) {
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this.list = list;
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}
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}
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@SuppressWarnings("unused")
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private static class WildcardListHolder2 {
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private List<?> list = new ArrayList<>();
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public List<?> getList() {
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return list;
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}
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public void setList(List<?> list) {
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this.list = list;
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}
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}
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@SuppressWarnings("unused")
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private static class NumberUpperBoundedWildcardListHolder {
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private List<? extends Number> list = new ArrayList<>();
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public List<? extends Number> getList() {
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return list;
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}
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public void setList(List<? extends Number> list) {
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this.list = list;
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}
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}
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@SuppressWarnings("unused")
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private static class NumberListHolder {
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private List<Number> list = new ArrayList<>();
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public List<Number> getList() {
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return list;
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}
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public void setList(List<Number> list) {
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this.list = list;
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}
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}
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@SuppressWarnings("unused")
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private static class IntegerListHolder1 {
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