[SW-2397] Automatically generate R configuration from Scala code

[jakubhava]

Example of a generated file:

#
#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

if (!exists("ConfUtils.getOption", mode = "function")) source(file.path("R", "ConfUtils.R"))

#' @export ExternalBackendConf
InternalBackendConf <- setRefClass("InternalBackendConf", methods = list(

    #
    # Getters
    #

    numH2OWorkers = function() { ConfUtils.getOption(invoke(jconf, "numH2OWorkers")) },

    drddMulFactor = function() { invoke(jconf, "drddMulFactor") },

    numRddRetries = function() { invoke(jconf, "numRddRetries") },

    defaultCloudSize = function() { invoke(jconf, "defaultCloudSize") },

    subseqTries = function() { invoke(jconf, "subseqTries") },

    hdfsConf = function() { ConfUtils.getOption(invoke(jconf, "hdfsConf")) },

    spreadRddRetriesTimeout = function() { invoke(jconf, "spreadRddRetriesTimeout") },

    nodeIcedDir = function() { ConfUtils.getOption(invoke(jconf, "nodeIcedDir")) },

    #
    # Setters
    #

    setNumH2OWorkers = function(value) { invoke(jconf, "setNumH2OWorkers", value); .self },

    setDrddMulFactor = function(value) { invoke(jconf, "setDrddMulFactor", value); .self },

    setNumRddRetries = function(value) { invoke(jconf, "setNumRddRetries", value); .self },

    setDefaultCloudSize = function(value) { invoke(jconf, "setDefaultCloudSize", value); .self },

    setSubseqTries = function(value) { invoke(jconf, "setSubseqTries", value); .self },

    setHdfsConf = function(value) { invoke(jconf, "setHdfsConf", value); .self },

    setSpreadRddRetriesTimeout = function(value) { invoke(jconf, "setSpreadRddRetriesTimeout", value); .self },

    setNodeIcedDir = function(value) { invoke(jconf, "setNodeIcedDir", value); .self }
))

[mn-mikke]

LGTM