Program: 93568
Project: 93568
Buggy source:
/** 
 * @param exchange
 * @param context
 * @throws Exception
 */
@Override public void handleRequest(HttpServerExchange exchange,RequestContext context) throws Exception {
  if (context.getMethod() == RequestContext.METHOD.GET || context.getMethod() == RequestContext.METHOD.OPTIONS || context.getMethod() == RequestContext.METHOD.DELETE) {
    next.handleRequest(exchange,context);
    return;
  }
  HeaderValues contentTypes=exchange.getRequestHeaders().get(Headers.CONTENT_TYPE);
  if (unsupportedContentType(contentTypes)) {
    ResponseHelper.endExchangeWithMessage(exchange,HttpStatus.SC_UNSUPPORTED_MEDIA_TYPE,"String_Node_Str" + Representation.HAL_JSON_MEDIA_TYPE + "String_Node_Str"+ Representation.JSON_MEDIA_TYPE+ "String_Node_Str"+ Representation.APP_FORM_URLENCODED_TYPE+ "String_Node_Str"+ Representation.MULTIPART_FORM_DATA_TYPE);
    return;
  }
  String _content=ChannelReader.read(exchange.getRequestChannel());
  DBObject content;
  try {
    content=(DBObject)JSON.parse(_content);
  }
 catch (  JSONParseException ex) {
    ResponseHelper.endExchangeWithMessage(exchange,HttpStatus.SC_NOT_ACCEPTABLE,"String_Node_Str",ex);
    return;
  }
  HashSet<String> keysToRemove=new HashSet<>();
  if (content == null) {
    context.setContent(null);
  }
 else {
    content.keySet().stream().filter(key -> key.startsWith("String_Node_Str") && !key.equals("String_Node_Str")).forEach(key -> {
      keysToRemove.add(key);
    }
);
    keysToRemove.stream().map(keyToRemove -> {
      content.removeField(keyToRemove);
      return keyToRemove;
    }
).forEach(keyToRemove -> {
      context.addWarning("String_Node_Str" + keyToRemove + "String_Node_Str");
    }
);
    if (context.isDetectObjectIds())     HALUtils.replaceStringsWithObjectIds(content);
    context.setContent(content);
  }
  next.handleRequest(exchange,context);
}

Fixed version (ground truth):
/** 
 * @param exchange
 * @param context
 * @throws Exception
 */
@Override public void handleRequest(HttpServerExchange exchange,RequestContext context) throws Exception {
  if (context.getMethod() == RequestContext.METHOD.GET || context.getMethod() == RequestContext.METHOD.OPTIONS || context.getMethod() == RequestContext.METHOD.DELETE) {
    next.handleRequest(exchange,context);
    return;
  }
  HeaderValues contentTypes=exchange.getRequestHeaders().get(Headers.CONTENT_TYPE);
  if (unsupportedContentType(contentTypes)) {
    ResponseHelper.endExchangeWithMessage(exchange,HttpStatus.SC_UNSUPPORTED_MEDIA_TYPE,"String_Node_Str" + Representation.HAL_JSON_MEDIA_TYPE + "String_Node_Str"+ Representation.JSON_MEDIA_TYPE+ "String_Node_Str"+ Representation.APP_FORM_URLENCODED_TYPE+ "String_Node_Str"+ Representation.MULTIPART_FORM_DATA_TYPE);
    return;
  }
  String _content=ChannelReader.read(exchange.getRequestChannel());
  DBObject content;
  try {
    content=(DBObject)JSON.parse(_content);
  }
 catch (  JSONParseException ex) {
    ResponseHelper.endExchangeWithMessage(exchange,HttpStatus.SC_NOT_ACCEPTABLE,"String_Node_Str",ex);
    return;
  }
  HashSet<String> keysToRemove=new HashSet<>();
  if (content == null) {
    context.setContent(null);
  }
 else {
    content.keySet().stream().filter(key -> key.startsWith("String_Node_Str") && !key.equals("String_Node_Str")).forEach(key -> {
      keysToRemove.add(key);
    }
);
    keysToRemove.stream().map(keyToRemove -> {
      content.removeField(keyToRemove);
      return keyToRemove;
    }
).forEach(keyToRemove -> {
      context.addWarning("String_Node_Str" + keyToRemove + "String_Node_Str");
    }
);
    if (context.isDetectObjectIds()) {
      Object keepId=null;
      if (context.getDocIdType() == RequestContext.DOC_ID_TYPE.STRING) {
        keepId=content.removeField("String_Node_Str");
      }
      HALUtils.replaceStringsWithObjectIds(content);
      if (keepId != null) {
        content.put("String_Node_Str",keepId);
      }
    }
    context.setContent(content);
  }
  next.handleRequest(exchange,context);
}