Build Problem with AnysoftKeyboard (Android)

I am trying to build AnysoftKeyboard in Android studio. I have java 9(jdk 9) and the appropriate ndk (android-ndk-r14b), as the creator in GitHub says. I have also changed the local.properties file to shows to the correct paths. Nevertheless I am still getting some errors. You can find below those errors.

Run tasks error : org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':base:compileDebugJavaWithJavac

java compiler errors : Caused by: java.lang.BootstrapMethodError: java.lang.NoClassDefFoundError: com/sun/tools/javac/util/JavacMessages$ResourceBundleHelper Caused by: java.lang.NoClassDefFoundError: com/sun/tools/javac/util/JavacMessages$ResourceBundleHelper Caused by: java.lang.ClassNotFoundException: com.sun.tools.javac.util.JavacMessages$ResourceBundleHelper

Here is a screenshot of the error : AnySoftKeyboard Compile Error , Run Tasks Error

The project uses gradle, in which I am not familiar with, so if I have missed any important step-point, please guide me to solve it.

Is there something that I am missing and getting these errors? What should I do? Thanks in advance.

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