don't generate nullable type for val with not-null initializer

src/org/jetbrains/jet/j2k/Converter.kt

@@ -224,10 +224,15 @@ public open class Converter() {
                     elementToElement(field.getArgumentList()))
         }
 
+        var kType = typeToType(field.getType())
+        if (field.hasModifierProperty(PsiModifier.FINAL) && isDefinitelyNotNull(field.getInitializer())) {
+            kType = kType.convertedToNotNull();
+        }
+
         return Field(Identifier(field.getName()!!),
                 docComments,
                 modifiers,
-                typeToType(field.getType()),
+                kType,
                 expressionToExpression(field.getInitializer(), field.getType()),
                 countWritingAccesses(field, psiClass))
     }
@@ -834,3 +839,9 @@ public open fun isAnnotatedAsNotNull(modifierList: PsiModifierList?): Boolean {
     }
     return false
 }
+
+public fun isDefinitelyNotNull(element: PsiElement?): Boolean = when(element) {
+    is PsiLiteralExpression -> element.getValue() != null
+    is PsiNewExpression -> true
+    else -> false
+}

src/org/jetbrains/jet/j2k/visitors/ElementVisitor.kt

@@ -6,6 +6,7 @@ import org.jetbrains.jet.j2k.ast.*
 import org.jetbrains.jet.j2k.ast.types.Type
 import java.util.List
 import org.jetbrains.jet.j2k.isAnnotatedAsNotNull
+import org.jetbrains.jet.j2k.isDefinitelyNotNull
 
 public open class ElementVisitor(val myConverter : Converter) : JavaElementVisitor() {
     protected var myResult : Element = Element.EMPTY_ELEMENT
@@ -20,9 +21,13 @@ public open class ElementVisitor(val myConverter : Converter) : JavaElementVisit
 
     public override fun visitLocalVariable(variable : PsiLocalVariable?) : Unit {
         val theVariable = variable!!
+        var kType = myConverter.typeToType(theVariable.getType(), isAnnotatedAsNotNull(theVariable.getModifierList()))
+        if (theVariable.hasModifierProperty(PsiModifier.FINAL) && isDefinitelyNotNull(theVariable.getInitializer())) {
+            kType = kType.convertedToNotNull();
+        }
         myResult = LocalVariable(Identifier(theVariable.getName()!!),
                 Converter.modifiersListToModifiersSet(theVariable.getModifierList()),
-                myConverter.typeToType(theVariable.getType(), isAnnotatedAsNotNull(theVariable.getModifierList())),
+                kType,
                 myConverter.expressionToExpression(theVariable.getInitializer(), theVariable.getType()))
     }
 

tests/testData/ast/field/file/valWithInit.kt

@@ -1,3 +1,3 @@
 open class C() {
-val f : Foo? = Foo(1, 2)
+val f : Foo = Foo(1, 2)
 }

tests/testData/ast/trait/class/interfaceWithFields.kt

@@ -1,7 +1,7 @@
 trait INode {
 class object {
-val IN : String? = "in"
-val AT : String? = "@"
+val IN : String = "in"
+val AT : String = "@"
 val COMMA_WITH_SPACE : String? = COMMA + SPACE
 }
 }

tests/testData/ast/trait/class/interfaceWithStaticFields.kt

@@ -1,7 +1,7 @@
 public trait INode {
 class object {
-public val IN : String? = "in"
-public val AT : String? = "@"
+public val IN : String = "in"
+public val AT : String = "@"
 public val COMMA_WITH_SPACE : String? = COMMA + SPACE
 }
 }