Java to Kotlin converter: and even more smartness about nullability

#KT-5162 Fixed

j2k/tests/testData/ast/nullability/MethodInvokedWithNullArg.java

@@ -0,0 +1,8 @@
+//file
+class C {
+    private void foo(String s){}
+
+    void bar() {
+        foo(null)
+    }
+}

j2k/tests/testData/ast/nullability/MethodInvokedWithNullArg.kt

@@ -0,0 +1,8 @@
+class C() {
+    private fun foo(s: String?) {
+    }
+
+    fun bar() {
+        foo(null)
+    }
+}

j2k/tests/testData/ast/nullability/MethodInvokedWithNullArg2.java

@@ -0,0 +1,10 @@
+//file
+class C {
+    public void foo(String s){}
+}
+
+class D {
+    void bar(C c) {
+        c.foo(null);
+    }
+}

j2k/tests/testData/ast/nullability/MethodInvokedWithNullArg2.kt

@@ -0,0 +1,10 @@
+class C() {
+    public fun foo(s: String?) {
+    }
+}
+
+class D() {
+    fun bar(c: C) {
+        c.foo(null)
+    }
+}

j2k/tests/testData/ast/nullability/MethodInvokedWithTernaryNullArg.java

@@ -0,0 +1,8 @@
+//file
+class C {
+    private void foo(String s){}
+
+    void bar(boolean b) {
+        foo(b ? "a" : null)
+    }
+}

j2k/tests/testData/ast/nullability/MethodInvokedWithTernaryNullArg.kt

@@ -0,0 +1,11 @@
+class C() {
+    private fun foo(s: String?) {
+    }
+
+    fun bar(b: Boolean) {
+        foo((if (b)
+            "a"
+        else
+            null))
+    }
+}

j2k/tests/testData/ast/nullability/MethodResultComparedWithNull.java

@@ -0,0 +1,12 @@
+//file
+interface I {
+    String getString();
+}
+
+class C {
+    void foo(I i) {
+        if (i.getString() == null) {
+            println("null")
+        }
+    }
+}

j2k/tests/testData/ast/nullability/MethodResultComparedWithNull.kt

@@ -0,0 +1,11 @@
+trait I {
+    public fun getString(): String?
+}
+
+class C() {
+    fun foo(i: I) {
+        if (i.getString() == null) {
+            println("null")
+        }
+    }
+}

j2k/tests/testData/ast/nullability/MethodReturnsNull.java

@@ -0,0 +1,11 @@
+//file
+class C {
+    String foo(boolean b) {
+        if (b) {
+            return "abc"
+        }
+        else {
+            return null
+        }
+    }
+}

j2k/tests/testData/ast/nullability/MethodReturnsNull.kt

@@ -0,0 +1,9 @@
+class C() {
+    fun foo(b: Boolean): String? {
+        if (b) {
+            return "abc"
+        } else {
+            return null
+        }
+    }
+}

j2k/tests/testData/ast/nullability/MethodReturnsNullInAnonymousClass.java

@@ -0,0 +1,19 @@
+import java.lang.Override;
+import java.lang.String;
+
+//file
+interface Getter {
+    String get()
+}
+
+class C {
+    String foo(boolean b) {
+        Getter getter = new Getter() {
+            @Override
+            public String get() {
+                return null;
+            }
+        };
+        return "";
+    }
+}

j2k/tests/testData/ast/nullability/MethodReturnsNullInAnonymousClass.kt

@@ -0,0 +1,16 @@
+import java.lang.Override
+
+trait Getter {
+    public fun get(): String
+}
+
+class C() {
+    fun foo(b: Boolean): String {
+        val getter = object : Getter() {
+            override fun get(): String? {
+                return null
+            }
+        }
+        return ""
+    }
+}

j2k/tests/testData/ast/nullability/MethodReturnsTernaryNull.java

@@ -0,0 +1,6 @@
+//file
+class C {
+    String foo(boolean b) {
+        return b ? "abc" : null
+    }
+}

j2k/tests/testData/ast/nullability/MethodReturnsTernaryNull.kt

@@ -0,0 +1,8 @@
+class C() {
+    fun foo(b: Boolean): String? {
+        return (if (b)
+            "abc"
+        else
+            null)
+    }
+}