@Override
	public long getID() {
		return Namespace.GLOBAL_NAMESPACE_ID;
	}
This method doesn't apply to the global symbol, since a program always has a global symbol 
and it can't be renamed. Therefore calling it will throw an UnsupportedOperationException.
return source the source of this symbol: default, imported, analysis, or user defined.
@throws UnsupportedOperationException whenever called.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/address/GlobalSymbol.java