client: use class methods on nvim-0.11 (fix #209)

lua/null-ls/client.lua

@@ -47,6 +47,7 @@ local get_root_dir = function(bufnr, cb)
     end
 end
 
+---@param new_client vim.lsp.Client
 local on_init = function(new_client, initialize_result)
     local capability_is_disabled = function(method)
         -- TODO: extract map to prevent future issues
@@ -56,7 +57,8 @@ local on_init = function(new_client, initialize_result)
     end
 
     -- null-ls broadcasts all capabilities on launch, so this lets us have finer control
-    new_client.supports_method = function(method)
+    ---@param method string
+    local supports_method = function(method)
         -- allow users to specifically disable capabilities
         if capability_is_disabled(method) then
             return false
@@ -72,6 +74,14 @@ local on_init = function(new_client, initialize_result)
         return methods.lsp[method] ~= nil
     end
 
+    if vim.fn.has("nvim-0.11") == 1 then
+        new_client.supports_method = function(_, method)
+            return supports_method(method)
+        end
+    else
+        new_client.supports_method = supports_method
+    end
+
     if c.get().on_init then
         c.get().on_init(new_client, initialize_result)
     end