Kapt3: Generate empty body for constructor and void methods

plugins/kapt3/testData/converter/dataClass.kt

@@ -1 +1,3 @@
-data class User(val firstName: String, val secondName: String, val age: Int)
+data class User(val firstName: String, val secondName: String, val age: Int) {
+    fun procedure() {}
+}

plugins/kapt3/testData/converter/dataClass.txt

@@ -3,6 +3,9 @@ public final class User {
     private final java.lang.String secondName;
     private final int age;
 
+    public final void procedure() {
+    }
+
     public final java.lang.String getFirstName() {
         return null;
     }
@@ -16,7 +19,6 @@ public final class User {
     }
 
     public void User(java.lang.String firstName, java.lang.String secondName, int age) {
-        return null;
     }
 
     public final java.lang.String component1() {