void (@NotNull PsiClass parent, @NotNull PsiClass exChild) { PsiReferenceList permitsList = parent.getPermitsList(); if (permitsList == null) return; PsiJavaCodeReferenceElement[] childRefs = permitsList.getReferenceElements(); PsiJavaCodeReferenceElement exChildRef = ContainerUtil.find(childRefs, ref -> ref.resolve() == exChild); if (exChildRef == null) return; exChildRef.delete(); if (childRefs.length != 1) return; PsiModifierList modifiers = parent.getModifierList(); if (modifiers == null) return; modifiers.setModifierProperty(PsiModifier.SEALED, false); }