question: public void addAdditionalSymbolClass ( FXGSymbolClass symbolClass ) { if ( additionalSymbolClasses == null ) additionalSymbolClasses = new ArrayList < FXGSymbolClass > ( ) ; additionalSymbolClasses . add ( symbolClass ) ; }
target:  An FXG node may have child nodes that also require a symbol class mapping that will be included along with the parent symbol for the compilation unit.