test: retore missing test

Author: diegomarquezp

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/gapic/protoparser/HttpRuleParser.java

@@ -151,6 +151,11 @@ private static Set<HttpBinding> validateAndConstructHttpBindings(
       for (int i = 0; i < subFields.length; i++) {
         String subFieldName = subFields[i];
         Field field = nestedMessage.fieldMap().get(subFieldName);
+        Preconditions.checkState(
+            field != null,
+            "Expected message %s to contain field %s but none found",
+            nestedMessage.name(),
+            subFieldName);
 
         // Each component of the JSON name uses the json_name annotation of the field,
         // or default to the field name

sdk-platform-java/gapic-generator-java/src/test/java/com/google/api/generator/gapic/protoparser/HttpRuleParserTest.java

@@ -79,6 +79,22 @@ void parseHttpAnnotation_multipleBindings() {
         .containsExactly("answer", "foo", "name", "test_to_verify.name", "type");
   }
 
+  @Test
+  void parseHttpAnnotation_missingFieldFromMessage() {
+    FileDescriptor testingFileDescriptor = TestingOuterClass.getDescriptor();
+    ServiceDescriptor testingService = testingFileDescriptor.getServices().get(0);
+    assertEquals("Testing", testingService.getName());
+
+    Map<String, Message> messages = Parser.parseMessages(testingFileDescriptor);
+
+    // VerityTest method.
+    MethodDescriptor rpcMethod =
+        testingService.getMethods().get(testingService.getMethods().size() - 1);
+    Message inputMessage = messages.get("com.google.showcase.v1beta1.CreateSessionRequest");
+    assertThrows(
+        IllegalStateException.class, () -> HttpRuleParser.parse(rpcMethod, inputMessage, messages));
+  }
+
   @Test
   void parseHttpAnnotation_shouldPutAllFieldsIntoQueryParamsIfPathParamAndBodyAreNotConfigured() {
     FileDescriptor fileDescriptor = HttpRuleParserTestingOuterClass.getDescriptor();