Calling this method seems to be important if one wants to obtain a Document instance for a
manually created PsiFile that's not been backed by a VirtualFile:
PsiFile file = parserDefinition.createFile(project, "foo", s).createPseudoPhysicalCopy();
Document d = PsiDocumentManager.getInstance(project).getDocument(file);
Unless createPseudoPhysicalCopy() is called, the returned Document will be null.
What's the recommended replacement using non-deprecated methods to achieve the effect
described above? The "for IDEA internal use only" hint isn't very helpful unfortunately as
this method seems to serve a purpose that's clearly within the scope of the OpenAPI.