Added test for KT-12124

idea/idea-completion/testData/basic/multifile/KT12124/KT12124.java

@@ -0,0 +1,7 @@
+class JavaClass {
+    public void setFoo(String value) {
+    }
+    public String getFoo() {
+        return "";
+    }
+}

idea/idea-completion/testData/basic/multifile/KT12124/KT12124.kt

@@ -0,0 +1,7 @@
+val v = JavaClass().apply {
+    foo = ""
+    foo.<caret>
+}
+
+// EXIST: length
+// EXIST: substring

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/MultiFileJvmBasicCompletionTestGenerated.java

@@ -185,6 +185,12 @@ public class MultiFileJvmBasicCompletionTestGenerated extends AbstractMultiFileJ
         doTest(fileName);
     }
 
+    @TestMetadata("KT12124")
+    public void testKT12124() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/multifile/KT12124/");
+        doTest(fileName);
+    }
+
     @TestMetadata("MoreSpecificExtensionGeneric")
     public void testMoreSpecificExtensionGeneric() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/basic/multifile/MoreSpecificExtensionGeneric/");