**Is your feature request related to a problem? Please describe.** * [Default implementation ](https://github.com/eclipse/xtext-core/blob/master/org.eclipse.xtext.ide/src/org/eclipse/xtext/ide/server/signatureHelp/ISignatureHelpService.java) * [Example test](https://github.com/eclipse/xtext-core/blob/master/org.eclipse.xtext.ide.tests/src/org/eclipse/xtext/ide/tests/server/SignatureHelpTest.java) * [VS Code Documentation](https://code.visualstudio.com/api/language-extensions/programmatic-language-features#help-with-function-and-method-signatures)
