DATACMNS-56 - PreferredConstructorDiscoverer does not throw an exception in case no preferred constructor is found.

spring-data-commons-core/src/main/java/org/springframework/data/mapping/PersistentEntity.java

@@ -21,7 +21,7 @@ public interface PersistentEntity<T, P extends PersistentProperty<P>> {
 	/**
 	 * Returns the {@link PreferredConstructor} to be used to instantiate objects of this {@link PersistentEntity}.
 	 * 
-	 * @return must never return {@literal null}.
+	 * @return {@literal null} in case no suitable constructor for automatic construction can be found.
 	 */
 	PreferredConstructor<T> getPreferredConstructor();
 

spring-data-commons-core/src/main/java/org/springframework/data/mapping/model/PreferredConstructorDiscoverer.java

@@ -50,8 +50,6 @@ public class PreferredConstructorDiscoverer<T> {
 	 */
 	protected PreferredConstructorDiscoverer(TypeInformation<T> owningType) {
 
-		boolean noArgConstructorFound = false;
-		int numberOfArgConstructors = 0;
 		Class<?> rawOwningType = owningType.getType();
 
 		for (Constructor<?> constructor : rawOwningType.getDeclaredConstructors()) {
@@ -65,24 +63,10 @@ public class PreferredConstructorDiscoverer<T> {
 				return;
 			}
 
-			// No-arg constructor trumps custom ones
-			if (this.constructor == null || preferredConstructor.isNoArgConstructor()) {
-				this.constructor = preferredConstructor;
-			}
-
 			if (preferredConstructor.isNoArgConstructor()) {
-				noArgConstructorFound = true;
-			} else {
-				numberOfArgConstructors++;
+				this.constructor = preferredConstructor;
 			}
 		}
-
-		if (!noArgConstructorFound && numberOfArgConstructors > 1) {
-			throw new IllegalArgumentException(
-					String.format("Multiple constructors with arguments found in class %s! Annotate " +
-							"one with @PersistenceConstructor explicitly to select it to be used in " +
-							"persistence operations.", rawOwningType.getName()));
-		}
 	}
 
 

spring-data-commons-core/src/test/java/org/springframework/data/mapping/PersistentEntitySpec.java

@@ -28,6 +28,5 @@ public abstract class PersistentEntitySpec {
 
 	public static void assertInvariants(PersistentEntity<?, ?> entity) {
 		assertThat(entity.getName(), is(notNullValue()));
-		assertThat(entity.getPreferredConstructor(), is(notNullValue()));
 	}
 }

spring-data-commons-core/src/test/java/org/springframework/data/mapping/PreferredConstructorDiscovererUnitTests.java

@@ -64,11 +64,12 @@ public class PreferredConstructorDiscovererUnitTests {
 	}
 
 
-	@Test(expected = IllegalArgumentException.class)
-	public void throwsExceptionForMultipleConstructorsAndNoNoArgConstructorWithoutAnnotation() {
+	@Test
+	public void doesNotThrowExceptionForMultipleConstructorsAndNoNoArgConstructorWithoutAnnotation() {
 
-		new PreferredConstructorDiscoverer<ClassWithMultipleConstructorsWithoutEmptyOne>(
+		PreferredConstructorDiscoverer<ClassWithMultipleConstructorsWithoutEmptyOne> discoverer = new PreferredConstructorDiscoverer<ClassWithMultipleConstructorsWithoutEmptyOne>(
 				ClassWithMultipleConstructorsWithoutEmptyOne.class);
+		assertThat(discoverer.getConstructor(), is(nullValue()));
 	}
 
 	@Test