DATACMNS-1082 - Skip synthetic constructors.

Constructor discovery no longer considers synthetic constructors for preferred constructor.

Original pull request: #225

Author: strelok1

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

@@ -34,6 +34,7 @@
  * 
  * @author Oliver Gierke
  * @author Christoph Strobl
+ * @author Roman Rodov
  */
 public class PreferredConstructorDiscoverer<T, P extends PersistentProperty<P>> {
 
@@ -75,6 +76,11 @@ protected PreferredConstructorDiscoverer(TypeInformation<T> type, Optional<Persi
 
 			PreferredConstructor<T, P> preferredConstructor = buildPreferredConstructor(candidate, type, entity);
 
+			// Synthetic constructors should not be considered
+			if (preferredConstructor.getConstructor().isSynthetic()) {
+				continue;
+			}
+
 			// Explicitly defined constructor trumps all
 			if (preferredConstructor.isExplicitlyAnnotated()) {
 				this.constructor = Optional.of(preferredConstructor);

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

@@ -31,6 +31,7 @@
  * Unit tests for {@link PreferredConstructorDiscoverer}.
  * 
  * @author Oliver Gierke
+ * @author Roman Rodov
  */
 public class PreferredConstructorDiscovererUnitTests<P extends PersistentProperty<P>> {
 
@@ -106,6 +107,34 @@ public void discoversInnerClassConstructorCorrectly() {
 		});
 	}
 
+	@Test // DATACMNS-1082
+	public void skipsSyntheticConstructor() {
+
+		PersistentEntity<SyntheticConstructor, P> entity = new BasicPersistentEntity<>(ClassTypeInformation.from(SyntheticConstructor.class));
+		PreferredConstructorDiscoverer<SyntheticConstructor, P> discoverer = new PreferredConstructorDiscoverer<>(entity);
+
+		assertThat(discoverer.getConstructor()).hasValueSatisfying(constructor -> {
+
+			PersistenceConstructor annotation = constructor.getConstructor().getAnnotation(PersistenceConstructor.class);
+			assertThat(annotation).isNotNull();
+			assertThat(constructor.getConstructor().isSynthetic()).isFalse();
+		});
+	}
+
+	static class SyntheticConstructor {
+		@PersistenceConstructor
+		private SyntheticConstructor(String x) {
+		}
+
+		class InnerSynthetic {
+			// Compiler will generate a synthetic constructor since
+			// SyntheticConstructor() is private.
+			InnerSynthetic() {
+				new SyntheticConstructor("");
+			}
+		}
+	}
+
 	static class EntityWithoutConstructor {
 
 	}