SEC-1994: explicit sourceCompatibility and targetCompatibility of 1.5 in Gradle build

gradle/javaprojects.gradle

@@ -1,6 +1,9 @@
 apply plugin: 'java'
 apply plugin: 'eclipse'
 
+sourceCompatibility = 1.5
+targetCompatibility = 1.5
+
 ext.springVersion = '3.0.7.RELEASE'
 ext.springLdapVersion = '1.3.1.RELEASE'
 ext.ehcacheVersion = '1.6.2'