Finally I figured out the problem.
For some reason the C project (the utility module) had wrong configuration in Deployment Assembly section of the project properties.
The /src/ folder was mapped on / deploy path. Instead the /src/main/java forlder should be mapped on / deploy path.
I still don't know how this happened (neved changed this section manually). May be there was a problem with the eclipse project configuration generation from maven configuration, but I don't know.
Thanks for the help,
Andrea