Note that only different set of declared exceptions or different return type do not distinguish two methods from each other. Constructors can only be pasted to an existing class as well. When pasted, the constructor's name is updated to the target class' name. The class' definition will be appended at the end of the source file, after all classes already defined there. Paste inside an existing class definition to form a new inner class.
New file is available on a package creating a new file with the same name as the class.
The new file will contain the pasted class' definition. Like the property sheet, changes made in the customizer are immediately reflected into the source text. Please separate page that shows how customizers look like and adds some more comments. The grouping nodes allow only creation of one type of elements, class node allows creation of all element types. The result is then written into the source file at an appropriate place.