Update to Java 1.6

Fixes gh-3756

core/src/test/java/org/springframework/security/core/JavaVersionTests.java

@@ -15,13 +15,13 @@
  */
 package org.springframework.security.core;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
 import java.io.DataInputStream;
 import java.io.InputStream;
 
 import org.junit.Test;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 /**
  *
  * @author Rob Winch
@@ -29,7 +29,7 @@ import org.junit.Test;
  */
 public class JavaVersionTests {
 
-	private static final int JDK5_CLASS_VERSION = 49;
+	private static final int JDK6_CLASS_VERSION = 50;
 
 	@Test
 	public void authenticationCorrectJdkCompatibility() throws Exception {
@@ -45,7 +45,7 @@ public class JavaVersionTests {
 			data.readInt();
 			data.readShort(); // minor
 			int major = data.readShort();
-			assertThat(major).isEqualTo(JDK5_CLASS_VERSION);
+			assertThat(major).isEqualTo(JDK6_CLASS_VERSION);
 		}
 		finally {
 			try {

gradle/javaprojects.gradle

@@ -5,8 +5,8 @@ apply plugin: 'javadocHotfix'
 apply plugin: 'propdeps'
 apply plugin: 'propdeps-maven'
 
-sourceCompatibility = 1.5
-targetCompatibility = 1.5
+sourceCompatibility = 1.6
+targetCompatibility = 1.6
 
 ext.apacheDsVersion = '1.5.5'
 ext.aspectjVersion = '1.8.4'