Queries with multiline strings inputs are still failing even using the backported method about graphql-ruby HOT 5 CLOSED

require "bundler/inline"

gemfile do
  gem "graphql", "2.3.0"
end

str1 = "
                mutation {
                  createRecord(data: {
                     dynamicFields: { string_test: \"avenue 1st
 2nd line\"},
                   })
                  { id, dynamicFields }\
               }
              "
puts str1.inspect
# "\n                mutation {\n                  createRecord(data: {\n                     dynamicFields: { string_test: \"avenue 1st\n 2nd line\"},\n                   })\n                  { id, dynamicFields }               }\n              "

str2 = GraphQL::Language.escape_single_quoted_newlines(str1)
# This one is different: it has an extra backslash ("\\n" instead of "\n"), showing that the newline was escaped:
puts str2.inspect
# "\n                mutation {\n                  createRecord(data: {\n                     dynamicFields: { string_test: \"avenue 1st\\n 2nd line\"},\n                   })\n                  { id, dynamicFields }               }\n              "

begin
  GraphQL.parse(str1)
rescue GraphQL::ParseError => err
  pp [err.line, err.col, err.message]
  # [4, 52, "Expected string or block string, but it was malformed"]
end

pp GraphQL.parse(str2).class
# GraphQL::Language::Nodes::Document