protected void populateBuiltInTypes() {
		int id = super.startTransaction("Populate");
		try {

			List<DataType> list = new ArrayList<>();
			ClassFilter filter = new BuiltInDataTypeClassExclusionFilter();
			List<BuiltInDataType> datatypes =
				ClassSearcher.getInstances(BuiltInDataType.class, filter);
			for (BuiltInDataType datatype : datatypes) {
				list.clear();
				findDataTypes(datatype.getName(), list);
				if (list.size() == 0) {
					super.resolve(datatype, null);
				}
				else if (!list.get(0).isEquivalent(datatype)) {
					Msg.showError(this, null, "Invalid BuiltIn Data Type",
						"BuiltIn datatype name collision between " +
							datatype.getClass().getSimpleName() + " and " +
							list.get(0).getClass().getSimpleName() + ", both named '" +
							datatype.getName() + "'");
				}
				else if (list.size() != 1) {
					throw new AssertException("Should be no duplicate named built-in types");
				}
			}
		}
		finally {
			super.endTransaction(id, true);
		}

	}
Add the built in data types to the default built in folder if they
were not found in any other category.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/BuiltInDataTypeManager.java