J2K: Speed-up add imports

nj2k/src/org/jetbrains/kotlin/nj2k/NewJavaToKotlinConverter.kt

@@ -92,14 +92,21 @@ class NewJavaToKotlinConverter(
 
     private fun KtFile.addImports(imports: Collection<FqName>) {
         val factory = KtPsiFactory(this)
-        var importList = importList
+
-        for (import in imports) {
+
-            val importDirective = factory.createImportDirective(ImportPath(import, isAllUnder = false))
+        if (imports.isEmpty()) return
-            if (importList == null) {
+        val importPsi = factory.createImportDirectives(
-                importList = addImportList(importDirective.parent as KtImportList)
+            imports.map { ImportPath(it, isAllUnder = false) }
-            } else {
+        )
-                importList.add(importDirective)
+        val createdImportList = importPsi.first().parent as KtImportList
-            }
+        val importList = importList
+        if (importList == null) {
+            addImportList(createdImportList)
+        } else {
+            val updatedList = if(importList.firstChild != null) {
+                createdImportList.addRangeBefore(importList.firstChild, importList.lastChild, createdImportList.firstChild)
+            } else createdImportList
+            importList.replace(updatedList)
         }
     }