[Regression] PHP language server fails to start

[ghost]

Steps to reproduce:

1. Create a php workspace, enable php language server
2. Open .php file

There's an error :

Error fetching server capabilities php. org.eclipse.lsp4j.jsonrpc.ResponseErrorException: Argument 2 passed to LanguageServer\LanguageServer::initialize() must be an instance of LanguageServer\Protocol\ClientCapabilities, string given, called in /home/user/che/ls-php/php-language-server/vendor/felixfbecker/advanced-json-rpc/lib/Dispatcher.php on line 164

This can be reproduced with the latest master.

[musienko-maxim]

Related selenium test: PhpProjectDebuggingTest

[kaloyan-raev]

I hit this too and did some debugging. The LSP protocol specifies that the InitializeParams.capabilities field is mandatory. It can be an empty object, but not undefined/null. So the PHP language server expects it in the initialize request and fails if it is not present in the JSON message body.

On the Che side the ServerInitializerImpl sets an empty ClientCapabilities object as the InitializeParams.capabilities, but then the InitializeParams object is serialized to something like this:

{
  "jsonrpc": "2.0",
  "id": "1",
  "method": "initialize",
  "params": {
    "processId": 24734,
    "rootPath": "/home/user/projects/myproj",
    "clientName": "EclipseChe"
  }
}

i.e. the capabilities object is missing.