move: leave classes in one file if they were together

java/java-tests/testData/refactoring/movePackageAsDir/multipleClassesInOneFile/after/src1/target/pack1/S1.java

@@ -4,4 +4,8 @@ public class S1{
   S11 s11;
 }
 
-class S11{}
+class S11{}
+
+class S12{}
+
+class S13{}

java/java-tests/testData/refactoring/movePackageAsDir/multipleClassesInOneFile/before/src1/pack1/S1.java

@@ -5,3 +5,7 @@ public class S1{
 }
 
 class S11{}
+
+class S12{}
+
+class S13{}