Resolve compiler warnings (#200)

* Fix: resolve compiler warnings
* Fix: supress warnings about internal api usage
See https://stackoverflow.com/a/19553686/6238618

build.gradle

@@ -12,6 +12,13 @@ apply plugin: 'com.github.johnrengelman.shadow'
 sourceCompatibility = '1.7'
 targetCompatibility = '1.7'
 
+compileJava {
+	// Suppress warnings about internal api usage - https://stackoverflow.com/a/19553686/6238618
+	options.fork = true
+	options.forkOptions.executable = 'javac'
+	options.compilerArgs << '-XDignore.symbol.file'
+}
+
 repositories {
 	jcenter()
 	mavenCentral()