Fix for KT-14205

If detected unfinished expression it passed through, added warning on action "Convert Java to Kotlin", if Java files contains syntax errors.

j2k/src/org/jetbrains/kotlin/j2k/ExpressionConverter.kt

@@ -546,7 +546,11 @@ class DefaultExpressionConverter : JavaElementVisitor(), ExpressionConverter {
             return
         }
 
-        val referenceName = expression.referenceName!!
+        val referenceName = expression.referenceName ?: run {
+            result = LiteralExpression(expression.text).assignNoPrototype()
+            return
+        }
+
         val target = expression.resolve()
 
         val isNullable = target is PsiVariable && isNullable(target)

j2k/testData/fileOrElement/issues/unfinishedReferenceExpression.java

@@ -0,0 +1,7 @@
+public class JavaClass {
+    public String v = "";
+    public void m(String s) {
+        s.
+        this.v.
+    }
+}

j2k/testData/fileOrElement/issues/unfinishedReferenceExpression.kt

@@ -0,0 +1,8 @@
+// ERROR: The expression cannot be a selector (occur after a dot)
+class JavaClass {
+    var v = ""
+    fun m(s: String) {
+        s.
+                this.v.
+    }
+}

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterForWebDemoTestGenerated.java

@@ -3003,6 +3003,12 @@ public class JavaToKotlinConverterForWebDemoTestGenerated extends AbstractJavaTo
             String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/issues/spaceBeforeAssignment.java");
             doTest(fileName);
         }
+
+        @TestMetadata("unfinishedReferenceExpression.java")
+        public void testUnfinishedReferenceExpression() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/issues/unfinishedReferenceExpression.java");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("j2k/testData/fileOrElement/kotlinApiAccess")

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterSingleFileTestGenerated.java

@@ -3003,6 +3003,12 @@ public class JavaToKotlinConverterSingleFileTestGenerated extends AbstractJavaTo
             String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/issues/spaceBeforeAssignment.java");
             doTest(fileName);
         }
+
+        @TestMetadata("unfinishedReferenceExpression.java")
+        public void testUnfinishedReferenceExpression() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/issues/unfinishedReferenceExpression.java");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("j2k/testData/fileOrElement/kotlinApiAccess")