Building FIQL queries is not a difficult process. Typical queries are simple enough to build them manually, for example:
More complex queries relying on 'and' or 'or' conditions (possibly composed with each other) and multiple operators are a bit more tedious and complex to build.
CXF 2.4.0 introduces a SearchConditionBuilder utility class (thanks to Andy Michalec) which can be used to simplify building FIQL queries and working with CXF JAX-RS endpoints already supporting FIQL queries.
Have a look please at this section, try SearchConditionBuilder and provide the feedback.