private void installCallingConventionWidget(JPanel parentPanel) {
		callingConventionComboBox = new GhidraComboBox<>();
		parentPanel.add(new GLabel("Calling Convention:"));
		parentPanel.add(callingConventionComboBox);
	}
Method must be invoked following construction to fetch function info 
and update components.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/AbstractEditFunctionSignatureDialog.java