Change JDK to 1.7 for Android packaging

Hi,
I wanted to add the newest Facebook SDK to my Android game but when packaging I see following error:

E:\Biblioteka\Dokumenty\Unreal Projects\gameDNAstudio\ChasingRobbers\Intermediate\Android\APK\JavaLibs\facebook\src\com\facebook\AccessToken.java:559: error: diamond operator is not supported in -source 1.5
MainFrameActions: Packaging (Android (All)): UnrealBuildTool:     [javac]         ArrayList<String> permissionsList = new ArrayList<>();
MainFrameActions: Packaging (Android (All)): UnrealBuildTool:     [javac]                                                           ^
MainFrameActions: Packaging (Android (All)): UnrealBuildTool:     [javac]   (use -source 7 or higher to enable diamond operator)

It’s happened because of wrong JDK version (1.6 instead of 1.7). I’ve installed JDK 1.7 but this error still occurs.

Could you help me?