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Merge branch '2.6.x' into 2.7.x
Closes gh-32167
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@ -28,11 +28,33 @@ import org.springframework.context.annotation.Conditional;
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* {@link Conditional @Conditional} that only matches when the specified classes are on
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* the classpath.
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* <p>
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* A {@link #value()} can be safely specified on {@code @Configuration} classes as the
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* annotation metadata is parsed by using ASM before the class is loaded. Extra care is
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* required when placed on {@code @Bean} methods, consider isolating the condition in a
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* separate {@code Configuration} class, in particular if the return type of the method
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* matches the {@link #value target of the condition}.
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* A {@code Class} {@link #value() value} can be safely specified on
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* {@code @Configuration} classes as the annotation metadata is parsed by using ASM before
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* the class is loaded. If a class reference cannot be used then a {@link #name() name}
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* {@code String} attribute can be used.
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* <p>
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* <b>Note:</b> Extra care must be taken when using {@code @ConditionalOnClass} on
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* {@code @Bean} methods where typically the return type is the target of the condition.
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* Before the condition on the method applies, the JVM will have loaded the class and
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* potentially processed method references which will fail if the class is not present. To
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* handle this scenario, a separate {@code @Configuration} class should be used to isolate
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* the condition. For example: <pre class="code">
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* @Configuration(proxyBeanMethods = false)
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* public class MyAutoConfiguration {
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*
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* @Configuration(proxyBeanMethods = false)
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* @ConditionalOnClass(SomeService.class)
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* public static class SomeServiceConfiguration {
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*
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* @Bean
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* @ConditionalOnMissingBean
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* public SomeService someService() {
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* return new SomeService();
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* }
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*
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* }
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*
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* }</pre>
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*
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* @author Phillip Webb
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* @since 1.0.0
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