Polishing.

Related ticket: GH-2252.

Author: odrotbohm

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/ValidationErrors.java

@@ -28,11 +28,10 @@
 import org.springframework.beans.PropertyAccessorUtils;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
-import org.springframework.data.mapping.PersistentPropertyAccessor;
 import org.springframework.data.mapping.context.PersistentEntities;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.validation.AbstractPropertyBindingResult;
-import org.springframework.validation.Errors;
 
 /**
  * An {@link Errors} implementation for use in the events mechanism of Spring Data REST. Customizes actual field lookup
@@ -92,22 +91,29 @@ public Object getPropertyValue(String propertyName) throws BeansException {
 			 * @param segment the property segment to look up, must not be {@literal null} or empty.
 			 * @return
 			 */
+			@Nullable
 			private Object lookupValueOn(Object value, String segment) {
 
-				Optional<PersistentEntity<?, ? extends PersistentProperty<?>>> entity = entities.getPersistentEntity(value.getClass());
+				Optional<PersistentEntity<?, ? extends PersistentProperty<?>>> entity = entities
+						.getPersistentEntity(value.getClass());
+
+				return getAccessor(entity, value, segment).getPropertyValue(segment);
+			}
+
+			private static ConfigurablePropertyAccessor getAccessor(
+					Optional<PersistentEntity<?, ? extends PersistentProperty<?>>> entity, Object value, String segment) {
+
 				if (!entity.isPresent()) {
-					return new DirectFieldAccessor(value).getPropertyValue(segment);
+					return PropertyAccessorFactory.forDirectFieldAccess(value);
 				}
 
 				PersistentProperty<?> property = entity //
 						.map(it -> it.getPersistentProperty(PropertyAccessorUtils.getPropertyName(segment))) //
 						.orElseThrow(() -> new NotReadablePropertyException(value.getClass(), segment));
 
-				ConfigurablePropertyAccessor accessor = property.usePropertyAccess() //
+				return property.usePropertyAccess() //
 						? PropertyAccessorFactory.forBeanPropertyAccess(value) //
 						: PropertyAccessorFactory.forDirectFieldAccess(value);
-
-				return accessor.getPropertyValue(segment);
 			}
 		};
 	}

spring-data-rest-core/src/test/java/org/springframework/data/rest/core/ValidationErrorsUnitTests.java

@@ -94,7 +94,7 @@ private static void expectedErrorBehavior(Errors errors) {
 			fail("Expected NotReadablePropertyException");
 		} catch (NotReadablePropertyException e) {}
 
-		assertThat(errors.getFieldValue("field")).isEqualTo((Object) "Hello");
+		assertThat(errors.getFieldValue("field")).isEqualTo("Hello");
 	}
 
 	static class Foo {
@@ -111,7 +111,8 @@ static class Qux {
 		String field = "World";
 	}
 
-	static class TestKeyValueMappingContext<E extends KeyValuePersistentEntity<?, P>, P extends KeyValuePersistentProperty<P>> extends KeyValueMappingContext<E, P> {
+	static class TestKeyValueMappingContext<E extends KeyValuePersistentEntity<?, P>, P extends KeyValuePersistentProperty<P>>
+			extends KeyValueMappingContext<E, P> {
 
 		@Override
 		protected boolean shouldCreatePersistentEntityFor(TypeInformation<?> type) {