DATACMNS-650 - Introduced CloseableIterator abstraction as a foundation for streaming of results.

A CloseableIterator abstracts the underlying result with support for releasing the associated resources via close() which can be transparently be used with try-with-resources in Java 7 since Closeable implements AutoCloseable from Java 7 on upwards. Added detector methods to QueryMethod to check whether the current method returns a Stream. 

Introduced ReflectionUtils.isJava8StreamType to safely detect whether the given type is assignable to a Java 8 Stream. Introduced CloseableIteratorDisposingRunnable that can be registered as a cleanup action on a Stream.

Original pull request: #116.

src/test/java/org/springframework/data/util/Java8StreamUtilsTests.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.util;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.junit.Test;
+
+/**
+ * Spring Data specific Java {@link Stream} utility methods and classes.
+ * 
+ * @author Thomas Darimont
+ * @since 1.8
+ */
+public class Java8StreamUtilsTests {
+
+	/**
+	 * @see DATACMNS-650
+	 */
+	@Test
+	public void shouldConvertAnIteratorToAStream() {
+
+		List<String> input = Arrays.asList("a", "b", "c");
+		Stream<String> stream = Java8StreamUtils.createStreamFromIterator(input.iterator());
+		List<String> output = stream.collect(Collectors.<String> toList());
+
+		assertThat(input, is(equalTo(output)));
+	}
+}