android_core ./gradlew debug can't find NodeMain [closed]

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[javac] Compiling 4 source files to /home/user/androidworkspace/android_core/android_benchmarks/bin/classes
[javac] /home/user/androidworkspace/android_core/android_benchmarks/src/org/ros/android/android_benchmarks/MainActivity.java:30:
error: MainActivity is not abstract and does not override abstract method
init(NodeMainExecutor) in RosActivity
[javac] public class MainActivity extends RosActivity {
[javac]        ^
[javac] /home/user/androidworkspace/android_core/android_benchmarks/src/org/ros/android/android_benchmarks/MainActivity.java:58:
error: cannot access NodeMain
[javac]     nodeMainExecutor.execute(rosTextView, nodeConfiguration);
[javac]                     ^
[javac]   class file for NodeMain not found
[javac] /home/user/androidworkspace/android_core/android_benchmarks/src/org/ros/android/android_benchmarks/MainActivity.java:54:
error: method does not override or implement a method from a supertype
[javac]   @Override
[javac]   ^
[javac] Note: /home/user/androidworkspace/android_core/android_benchmarks/src/org/ros/android/android_benchmarks/MainActivity.java
uses unchecked or unsafe operations.
[javac] Note: Recompile with -Xlint:unchecked for details.
[javac] 3 errors

BUILD FAILED
/home/user/adt-bundle-linux-x86_64/sdk/tools/ant/build.xml:710:
The following error occurred while executing this line:
/home/user/adt-bundle-linux-x86_64/sdk/tools/ant/build.xml:723:
Compile failed; see the compiler error output for details.

Total time: 3 seconds

FAILURE: Build failed with an exception.

* What went wrong: Execution failed for task ':android_benchmarks:debug'.
Command 'ant' finished with (non-zero) exit value 1.

Somehow the compilation fails on finding NodeMain, any idea on how to fix this error?