[hotfix] Java-7-ify the ExecutionConfig class

flink-core/src/main/java/org/apache/flink/api/common/ExecutionConfig.java

@@ -88,7 +88,7 @@ public class ExecutionConfig implements Serializable {
 	/** If set to true, progress updates are printed to System.out during execution */
 	private boolean printProgressDuringExecution = true;
 
-	private GlobalJobParameters globalJobParameters = null;
+	private GlobalJobParameters globalJobParameters;
 
 	private long autoWatermarkInterval = 0;
 
@@ -99,17 +99,17 @@ public class ExecutionConfig implements Serializable {
 	// Serializers and types registered with Kryo and the PojoSerializer
 	// we store them in linked maps/sets to ensure they are registered in order in all kryo instances.
 
-	private final LinkedHashMap<Class<?>, SerializableSerializer<?>> registeredTypesWithKryoSerializers = new LinkedHashMap<Class<?>, SerializableSerializer<?>>();
+	private final LinkedHashMap<Class<?>, SerializableSerializer<?>> registeredTypesWithKryoSerializers = new LinkedHashMap<>();
 
-	private final LinkedHashMap<Class<?>, Class<? extends Serializer<?>>> registeredTypesWithKryoSerializerClasses = new LinkedHashMap<Class<?>, Class<? extends Serializer<?>>>();
+	private final LinkedHashMap<Class<?>, Class<? extends Serializer<?>>> registeredTypesWithKryoSerializerClasses = new LinkedHashMap<>();
 
-	private final LinkedHashMap<Class<?>, SerializableSerializer<?>> defaultKryoSerializers = new LinkedHashMap<Class<?>, SerializableSerializer<?>>();
+	private final LinkedHashMap<Class<?>, SerializableSerializer<?>> defaultKryoSerializers = new LinkedHashMap<>();
 
-	private final LinkedHashMap<Class<?>, Class<? extends Serializer<?>>> defaultKryoSerializerClasses = new LinkedHashMap<Class<?>, Class<? extends Serializer<?>>>();
+	private final LinkedHashMap<Class<?>, Class<? extends Serializer<?>>> defaultKryoSerializerClasses = new LinkedHashMap<>();
 
-	private final LinkedHashSet<Class<?>> registeredKryoTypes = new LinkedHashSet<Class<?>>();
+	private final LinkedHashSet<Class<?>> registeredKryoTypes = new LinkedHashSet<>();
 
-	private final LinkedHashSet<Class<?>> registeredPojoTypes = new LinkedHashSet<Class<?>>();
+	private final LinkedHashSet<Class<?>> registeredPojoTypes = new LinkedHashSet<>();
 
 	// --------------------------------------------------------------------------------------------