Open Declaration (Ctrl + Click / F3) does not collect declarations

[travkin79]

I checked an issue in a CDT LSP editor concerning the "open declaration" feature. In a C++ code example, I was able to jumpt to a method's definition, but not to its declaration.

I checked the LSP4E implementation in org.eclipse.lsp4e.operations.declaration.OpenDeclarationHyperlinkDetector and it turns out, the LSP endpoint textDocument/declaration is not used at all (see source code excerpt). I think, in addition to the definitions (and type definitions and implementations), the declarations should be collected here, too.

Are there any objections?