No need to call .dup since Array#+ doesn't mutate the original array
No need to call .dup since Array#+ doesn't mutate the original array

See docs for Array#+

http://ruby-doc.org/core-1.8.7/Array.html#method-i-2B
http://ruby-doc.org/core-1.9.3/Array.html#method-i-2B
http://ruby-doc.org/core-2.2.3/Array.html#method-i-2B

braintree/braintree_ruby,braintree/braintree_ruby