DATACMNS-31 - Added null check to SimpleTypeHolder.isSimpleType(…).

The MappingBeanHelper mentioned in the ticket was recently replaced by SimpleTypeHolder.

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

@@ -115,6 +115,7 @@ public class SimpleTypeHolder {
 	 * @return
 	 */
 	public boolean isSimpleType(Class<?> type) {
+		Assert.notNull(type);
 		for (Class<?> clazz : simpleTypes) {
 			if (type == clazz || clazz.isAssignableFrom(type)) {
 				return true;

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

@@ -39,6 +39,15 @@ public class SimpleTypeHolderUnitTests {
 	public void rejectsNullOriginal() {
 		new SimpleTypeHolder(new HashSet<Class<?>>(), null);
 	}
+
+	/**
+	 * @see DATACMNS-31
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullTypeForIsSimpleTypeCall() {
+		SimpleTypeHolder holder = new SimpleTypeHolder();
+		holder.isSimpleType(null);
+	}
 	
 	@Test
 	public void addsDefaultTypes() {