DATACMNS-68 - Fixed potential NPE in AbstractPersistentProperty.

Fixed ClassTypeInformation returning correct component types for types implementing or extending a Collection or Map type.

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

@@ -47,10 +47,13 @@ public abstract class AbstractPersistentProperty<P extends PersistentProperty<P>
 	protected final PersistentEntity<?, P> owner;
 	private final SimpleTypeHolder simpleTypeHolder;
 
-	public AbstractPersistentProperty(Field field, PropertyDescriptor propertyDescriptor, PersistentEntity<?, P> owner, SimpleTypeHolder simpleTypeHolder) {
-		
+	public AbstractPersistentProperty(Field field, PropertyDescriptor propertyDescriptor, PersistentEntity<?, P> owner,
+			SimpleTypeHolder simpleTypeHolder) {
+
+		Assert.notNull(field);
 		Assert.notNull(simpleTypeHolder);
-		
+		Assert.notNull(owner);
+
 		this.name = field.getName();
 		this.rawType = field.getType();
 		this.information = owner.getTypeInformation().getProperty(this.name);
@@ -144,7 +147,13 @@ public abstract class AbstractPersistentProperty<P extends PersistentProperty<P>
 	}
 
 	public Class<?> getComponentType() {
-		return isMap() || isCollection() ? information.getComponentType().getType() : null;
+
+		if (!isMap() && !isCollection()) {
+			return null;
+		}
+
+		TypeInformation<?> componentType = information.getComponentType();
+		return componentType == null ? null : componentType.getType();
 	}
 
 	/* (non-Javadoc)

spring-data-commons-core/src/main/java/org/springframework/data/util/ClassTypeInformation.java

@@ -18,8 +18,10 @@ package org.springframework.data.util;
 import java.lang.reflect.Method;
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
+import java.util.Collection;
 import java.util.Map;
 
+import org.springframework.core.GenericCollectionTypeResolver;
 import org.springframework.util.Assert;
 
 /**
@@ -79,19 +81,18 @@ public class ClassTypeInformation<S> extends TypeDiscoverer<S> {
 		return type;
 	}
 
-	/* (non-Javadoc)
-		 * @see org.springframework.data.util.TypeDiscoverer#getComponentType()
-		 */
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.util.TypeDiscoverer#getComponentType()
+	 */
 	@Override
-	@SuppressWarnings({"rawtypes", "unchecked"})
 	public TypeInformation<?> getComponentType() {
 
 		if (type.isArray()) {
 			return createInfo(resolveArrayType(type));
 		}
 
-		TypeVariable<?>[] typeParameters = type.getTypeParameters();
-		return typeParameters.length > 0 ? new TypeVariableTypeInformation(typeParameters[0], this.getType(), this) : null;
+		return super.getComponentType();
 	}
 
 	private static Type resolveArrayType(Class<?> type) {

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

@@ -0,0 +1,62 @@
+package org.springframework.data.mapping.model;
+
+import java.beans.PropertyDescriptor;
+import java.lang.reflect.Field;
+import java.util.TreeSet;
+
+import org.junit.Test;
+import org.springframework.data.mapping.Association;
+import org.springframework.data.mapping.PersistentEntity;
+import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.util.ReflectionUtils;
+
+/**
+ * Unit tests for {@link AbstractPersistentProperty}.
+ * 
+ * @author Oliver Gierke
+ */
+public class AbstractPersistentPropertyUnitTests {
+
+	/**
+	 * @see DATACMNS-68
+	 * @throws Exception
+	 */
+	@Test
+	public void discoversComponentTypeCorrectly() throws Exception {
+
+		BasicPersistentEntity<TestClassComplex, SamplePersistentProperty> entity = new BasicPersistentEntity<TestClassComplex, SamplePersistentProperty>(
+				ClassTypeInformation.from(TestClassComplex.class));
+		
+		Field field = ReflectionUtils.findField(TestClassComplex.class, "testClassSet");
+		
+		SamplePersistentProperty property = new SamplePersistentProperty(field, null, entity, new SimpleTypeHolder());
+		property.getComponentType();
+	}
+
+	@SuppressWarnings("serial")
+	class TestClassSet extends TreeSet<Object> {
+	}
+
+	class TestClassComplex {
+
+		String id;
+		TestClassSet testClassSet;
+	}
+
+	class SamplePersistentProperty extends AbstractPersistentProperty<SamplePersistentProperty> {
+
+		public SamplePersistentProperty(Field field, PropertyDescriptor propertyDescriptor,
+				PersistentEntity<?, SamplePersistentProperty> owner, SimpleTypeHolder simpleTypeHolder) {
+			super(field, propertyDescriptor, owner, simpleTypeHolder);
+		}
+
+		public boolean isIdProperty() {
+			return false;
+		}
+
+		@Override
+		protected Association<SamplePersistentProperty> createAssociation() {
+			return null;
+		}
+	}
+}