HttpTrigger with empty methods does not to respond to all methods

Based on the [HttpTrigger docs](https://docs.microsoft.com/en-us/azure/azure-functions/functions-bindings-http-webhook#trigger---configuration), if the methods are left empty in the HttpTrigger definition, it should respond to all methods.

When not explicitly defined, the HttpTrigger annotation in Java generates an empty `methods` array in function.json. This means the function doesn't respond to any HTTP methods at all and is inconsistent with the docs and the way the trigger works in other languages.

Start with the Java HttpTrigger annotation and the generation of function.json when methods are omitted. Verify how an empty methods array is produced and confirm that the completed behavior allows the function to respond to all HTTP methods, consistent with the linked documentation and other languages.

Written by the indexing model from the issue text.