AbstractStringBuilder, StringBuilder and java.io.File annotated with nullable/notnull

compiler/testData/diagnostics/tests/checkArguments/SpreadVarargs.kt

@@ -75,7 +75,7 @@ fun join(x : Int, vararg a : String) : String {
     for (s in a) {
         b.append(s)
     }
-    return b.toString()!!
+    return b.toString()
 }
 
 fun <T> joinG(x : Int, vararg a : T) : String {
@@ -83,7 +83,7 @@ fun <T> joinG(x : Int, vararg a : T) : String {
     for (s in a) {
         b.append(s)
     }
-    return b.toString()!!
+    return b.toString()
 }
 
 fun <T> joinT(<!UNUSED_PARAMETER!>x<!> : Int, vararg <!UNUSED_PARAMETER!>a<!> : T) : T? {

compiler/testData/diagnostics/tests/regressions/DoubleDefine.kt

@@ -52,7 +52,7 @@ fun main(args: Array<String>) {
   System.out.println("Your numbers: " + prompt)
   System.out.println("Enter your expression:")
   val reader = BufferedReader(InputStreamReader(System.`in`))
-  val expr = StringBuilder(reader.readLine())
+  val expr = StringBuilder(reader.readLine()!!)
   try {
     val result = evaluate(expr, numbers)
     if (result != 24)