@Override
	public boolean isInsertAllowed(int rowIndex, DataType datatype) {
		if (datatype.equals(DataType.DEFAULT)) {
			return false;
		}
		return rowIndex <= viewComposite.getNumComponents();
	}
Returns whether or not insertion of the specified component is allowed
at the specified index.

@param rowIndex index of the row in the union table.
@param datatype the data type to be inserted.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/compositeeditor/UnionEditorModel.java