[Java] add missing JNI exception checks to fix warnings (#2405)
[Java] add missing JNI exception checks to fix warnings (#2405)

* add missing JNI exception checks to fix warnings

* updated based on comments

* removed rethrow logic

* replace tabs with spaces

henry0312/LightGBM,microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,microsoft/LightGBM