How to develop or change stuff in GraphHopper and use IDE features like debugging etc?

Open Source Routing Engine
8

Now i have another problem. I wanted to add my own FlagEncoder, outside Graphhopper.
The problem i have is, that factor inside EncodedValue has protected acces.
I recieve this error:

[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.3:compile (default-compile) on project custom: Compilation failure
[ERROR] [path]/MyFlagEncoder.java:[275,32] error: factor has protected access in EncodedValue