def get_header_value(key)
      _key, value = @headers.detect { |k, _v| k.to_s.downcase == key.to_s.downcase }

      if value
        values = Utils.wrap_array(value)

        if values.size == 1
          values[0]
        else
          values
        end
      end
    end
def get_header_value(key)
      _key, value = @headers.detect { |k, _v| k.to_s.downcase == key.to_s.downcase }

      if value
        values = Utils.wrap_array(value)

        if values.size == 1
          values[0]
        else
          values
        end
      end
    end
Get value from header. Takes care of:

 - Unwrapping multiple values.
 - Handling casing difference in header name.