given and declared do not work together

I have the following params definition:

        module FooParams
          extend Grape::API::Helpers

          params :bar_params do
            requires :a, type: String
          end

          params :baz_params do
            requires :b, type: String
          end

          params :foo_params do
            requires :type, type: String
            given type: -> (val) { val == 'Bar' } do
              requires :foo, type: Hash do
                use :bar_params
              end
            end
            given type: -> (val) { val == 'Baz' } do
              requires :foo, type: Hash do
                use :baz_params
              end
            end
          end
        end

The foo_params are used in this post:

        resource :foos do
          helpers FooParams

          params do
            use :foo_params
          end

          post do
            if params[:type] == 'Bar'
              puts "original a: '#{params[:foo][:a]}'"
              puts "declared a: '#{declared(params)[:foo][:a]}'"
            end
            {}
          end
        end

Now when I call POST /foos with {type: 'Bar', {foo: {a: 'letter A'}}}, I get the following output:

original a: 'letter A'
declared a: ''

If I remove the latter given definition (val == 'Baz'), it prints:

original a: 'letter A'
declared a: 'letter A'

Reproduce the issue with the shown FooParams definitions and POST /foos request. Start by tracing how the given and declared parameter handling uses multiple conditional branches. Done means declared(params) retains foo.a when type is Bar even when the Baz branch is also defined, with a regression test covering both branches.