DATACMNS-320 - Be less restrictive in finding mapping ambiguities.

So far we threw exceptions in case we find the same exception on getters *and* setters. We now allow this scenario in case the annotations are semantically equivalent.

Author: odrotbohm

src/main/java/org/springframework/data/mapping/model/AnnotationBasedPersistentProperty.java

@@ -82,7 +82,7 @@ private final void populateAnnotationCache(Field field) {
 
 				Class<? extends Annotation> annotationType = annotation.annotationType();
 
-				if (annotationCache.containsKey(annotationType)) {
+				if (annotationCache.containsKey(annotationType) && !annotationCache.get(annotationType).equals(annotation)) {
 					throw new MappingException(String.format("Ambiguous mapping! Annotation %s configured "
 							+ "multiple times on accessor methods of property %s in class %s!", annotationType, getName(), getOwner()
 							.getType().getName()));

src/test/java/org/springframework/data/mapping/model/AbstractAnnotationBasedPropertyUnitTests.java

@@ -136,6 +136,7 @@ static class Sample {
 		String field;
 		String getter;
 		String setter;
+		String doubleMapping;
 
 		@MyAnnotationAsMeta
 		String meta;
@@ -157,6 +158,16 @@ public void setSetter(String setter) {
 		public String getOverride() {
 			return override;
 		}
+
+		@MyAnnotation
+		public String getDoubleMapping() {
+			return doubleMapping;
+		}
+
+		@MyAnnotation
+		public void setDoubleMapping(String doubleMapping) {
+			this.doubleMapping = doubleMapping;
+		}
 	}
 
 	static class InvalidSample {
@@ -168,7 +179,7 @@ public String getMeta() {
 			return meta;
 		}
 
-		@MyAnnotation
+		@MyAnnotation("foo")
 		public void setMeta(String meta) {
 			this.meta = meta;
 		}