DATACMNS-243 - Allow dedicated control over the access type for properties.

Introduced @AccessType annotation to allow user to control the way property values are accessed. The default is field access. Improved the property detection mechanism to also inspect all PropertyDescriptors not backed by a field and add them if property access is defined for the property or type. We also keep property accessors for interfaces as they strongly indicate property access to be used (as they cannot be field backed by definition).

The BeanWrapper doesn't take a useFieldAccess attribute anymore as the access type is solely derived from the given PersistentProperty now. AnnotationBasedPersistentProperty now also rejects properties with the very same annotation both on the field and on an accessor.

src/main/java/org/springframework/data/annotation/AccessType.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to define how Spring Data shall access values of persistent properties. Can either be {@link Type#FIELD}
+ * or {@link Type#PROPERTY}. Default is field access.
+ * 
+ * @author Oliver Gierke
+ */
+@Documented
+@Target({ ElementType.ANNOTATION_TYPE, ElementType.TYPE, ElementType.FIELD, ElementType.METHOD, })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface AccessType {
+
+	/**
+	 * The access type to be used.
+	 * 
+	 * @return
+	 */
+	Type value();
+
+	enum Type {
+		FIELD, PROPERTY;
+	}
+}