Support @value meta-annotations and expose MergedAnnotations on PreferredConstructor parameters.

We now support composed annotation that are annotated with `@Value`. we also expose MergedAnnotations through PreferredConstructor.Parameter for further use by store modules that want to inspect constructor argument annotations.

Closes: #2332
Original Pull Request: #2333

Author: mp911de

src/main/java/org/springframework/data/mapping/PreferredConstructor.java

@@ -23,6 +23,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.data.annotation.PersistenceConstructor;
 import org.springframework.data.util.Lazy;
 import org.springframework.data.util.TypeInformation;
@@ -175,6 +176,7 @@ public static class Parameter<T, P extends PersistentProperty<P>> {
 
 		private final @Nullable String name;
 		private final TypeInformation<T> type;
+		private final MergedAnnotations annotations;
 		private final String key;
 		private final @Nullable PersistentEntity<T, P> entity;
 
@@ -199,7 +201,8 @@ public Parameter(@Nullable String name, TypeInformation<T> type, Annotation[] an
 
 			this.name = name;
 			this.type = type;
-			this.key = getValue(annotations);
+			this.annotations = MergedAnnotations.from(annotations);
+			this.key = getValue(this.annotations);
 			this.entity = entity;
 
 			this.enclosingClassCache = Lazy.of(() -> {
@@ -216,12 +219,12 @@ public Parameter(@Nullable String name, TypeInformation<T> type, Annotation[] an
 		}
 
 		@Nullable
-		private static String getValue(Annotation[] annotations) {
+		private static String getValue(MergedAnnotations annotations) {
 
-			return Arrays.stream(annotations)//
-					.filter(it -> it.annotationType() == Value.class)//
-					.findFirst().map(it -> ((Value) it).value())//
-					.filter(StringUtils::hasText).orElse(null);
+			return annotations.get(Value.class) //
+					.getValue("value", String.class) //
+					.filter(StringUtils::hasText) //
+					.orElse(null);
 		}
 
 		/**
@@ -243,6 +246,16 @@ public TypeInformation<T> getType() {
 			return type;
 		}
 
+		/**
+		 * Merged annotations that this parameter is annotated with.
+		 *
+		 * @return
+		 * @since 2.5
+		 */
+		public MergedAnnotations getAnnotations() {
+			return annotations;
+		}
+
 		/**
 		 * Returns the raw resolved type of the parameter.
 		 *

src/test/java/org/springframework/data/mapping/PreferredConstructorDiscovererUnitTests.java

@@ -17,9 +17,15 @@
 
 import static org.assertj.core.api.Assertions.*;
 
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
 import java.util.Iterator;
 
 import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.data.annotation.PersistenceConstructor;
 import org.springframework.data.mapping.PreferredConstructor.Parameter;
 import org.springframework.data.mapping.PreferredConstructorDiscovererUnitTests.Outer.Inner;
@@ -135,6 +141,16 @@ void capturesSuperClassEnclosingTypeParameterOfNonStaticInnerClass() {
 				});
 	}
 
+	@Test // GH-2332
+	void detectsMetaAnnotatedValueAnnotation() {
+
+		assertThat(PreferredConstructorDiscoverer.discover(ClassWithMetaAnnotatedParameter.class)).satisfies(ctor -> {
+
+			assertThat(ctor.getParameters().get(0).getSpelExpression()).isEqualTo("${hello-world}");
+			assertThat(ctor.getParameters().get(0).getAnnotations()).isNotNull();
+		});
+	}
+
 	static class SyntheticConstructor {
 		@PersistenceConstructor
 		private SyntheticConstructor(String x) {}
@@ -204,4 +220,18 @@ public NonStaticInnerWithGenericArgUsedInCtor(T value) {
 			super(value);
 		}
 	}
+
+	static class ClassWithMetaAnnotatedParameter {
+
+		ClassWithMetaAnnotatedParameter(@MyValue String value) {
+
+		}
+	}
+
+	@Target({ ElementType.PARAMETER, })
+	@Retention(RetentionPolicy.RUNTIME)
+	@Value("${hello-world}")
+	@interface MyValue {
+
+	}
 }