static Structure createPlaceHolderStructure(String dtName, Demangled namespace) {
		if (StringUtils.isBlank(dtName)) {
			throw new IllegalArgumentException("Name cannot be blank");
		}
		StructureDataType structDT = new StructureDataType(dtName, 0);
		structDT.setDescription("PlaceHolder Structure");
		structDT.setCategoryPath(getDemanglerCategoryPath(namespace));
		return structDT;
	}
Find non-builtin type
@param dataTypeManager data type manager to be searched
@param dtName name of data type
@param namespace namespace associated with dtName or null if not applicable.  If specified,
a namespace-base category path will be given precedence.
@return data type if found, otherwise null.
@see DataTypeUtilities#findDataType(DataTypeManager, ghidra.program.model.symbol.Namespace, String, Class) for similar namespace
based search.
Ghidra/Features/Base/src/main/java/ghidra/app/util/demangler/DemangledDataType.java