Make metafacture-core build on Java 8 (fix #182)

Switches to antlr 3.5.2 and fixes test case which fails
due to changes in the garbage collection in the Java 8 jvm.

This commit is cherry-picked from commit
 * 9656209
in https://github.com/hbz/metafacture-core/

Author: cboehme

pom.xml

@@ -61,7 +61,7 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<targetJdk>1.6</targetJdk>
-		<antlr.version>3.5.1</antlr.version>
+		<antlr.version>3.5.2</antlr.version>
 	</properties>
 
 	<scm>

src/test/java/org/culturegraph/mf/stream/pipe/sort/AbstractTripleSortTest.java

@@ -58,9 +58,11 @@ public void shouldNotFailIfFlushingBeforeFirstRecord() {
 	 * This test case may throw fail unexpectedly as it relies on the
 	 * garbage collector to run when calling {@code System.gc()}. This
 	 * is not guaranteed by the JVM.
+	 *
+	 * @throws InterruptedException
 	 */
 	@Test
-	public void issue192ShouldUnregisterFromTheJVMToNotCauseMemoryLeak() {
+	public void issue192ShouldUnregisterFromTheJVMToNotCauseMemoryLeak() throws InterruptedException {
 
 		// Get weak reference for checking whether the object was actually freed later:
 		final ReferenceQueue<AbstractTripleSort> refQueue = new ReferenceQueue<AbstractTripleSort>();
@@ -71,6 +73,9 @@ public void issue192ShouldUnregisterFromTheJVMToNotCauseMemoryLeak() {
 
 		System.gc();
 
+		// Wait a tiny bit since GC Thread is not immediately done in Java 8
+		Thread.sleep(1);
+
 		assertTrue(weakRef.isEnqueued());
 	}