public FunctionDefinition getFunctionDefinition() {
			return functionDefinition;
		}
Construct signature override for called function
@param tool active tool
@param func function from which program access is achieved and supply of preferred 
datatypes when parsing signature
@param signature initial prototype signature to be used
@param conv initial calling convention
Ghidra/Features/Decompiler/src/main/java/ghidra/app/plugin/core/decompile/actions/OverridePrototypeAction.java