Be careful with ruby 'Hash.merge!'
Modifying a hash within the function causes a side effect of modifying the caller’s hash
extracted from here: https://github.com/ruby-grape/grape/pull/1386#discussion_r62328712
Modifying a hash within the function causes a side effect of modifying the caller’s hash
extracted from here: https://github.com/ruby-grape/grape/pull/1386#discussion_r62328712