public Symbol getExtSymbol() {
		return extSymbol;
	}
Create an external function in the specified external namespace.
@param externalParentNamespace the external parent namespace where the named function should be created (required)
@param name function name (required)
@param address the address of the function's entry point in the external library (optional)
@param source the source type for this external function
Ghidra/Features/Base/src/main/java/ghidra/app/cmd/function/CreateExternalFunctionCmd.java