Copy: Copy entire file if it contains just a selected declaration

idea/testData/refactoring/copy/refToImportJavaStaticField/after/foo/test.kt

@@ -5,3 +5,7 @@ import foo.J.JJJ
 fun test() {
     val x = JJJ
 }
+
+fun dummy() {
+
+}

idea/testData/refactoring/copy/refToImportJavaStaticField/before/foo/test.kt

@@ -5,3 +5,7 @@ import foo.J.JJJ
 fun <caret>test() {
     val x = JJJ
 }
+
+fun dummy() {
+
+}