You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20180607175050_properties_to_jsonb.rb
    path of file: ./repos/arvados/services/api/db/migrate
    
    the code of the file until where you have to start completion: # Copyright (C) The Arvados Authors. All rights reserved.
#
# SPDX-License-Identifier: AGPL-3.0

require './db/migrate/20161213172944_full_text_search_indexes'

class PropertiesToJsonb 
    
  def up
    @@tables_columns.each do |table, column|
      # Drop the FT index before changing column type to avoid
      # "PG::DatatypeMismatch: ERROR: COALESCE types jsonb and text
      # cannot be matched".
      ActiveRecord::Base.connection.execute "DROP INDEX IF EXISTS #{table}_full_text_search_idx"
      ActiveRecord::Base.connection.execute "ALTER TABLE #{table} ALTER COLUMN #{column} TYPE jsonb USING #{column}::jsonb"
      ActiveRecord::Base.connection.execute "CREATE INDEX #{table}_index_on_#{column} ON #{table} USING gin (#{column})"
    end
    FullTextSearchIndexes.new.replace_index("container_requests")
  end