public static byte[] createCompositeKey(byte[] tableName, byte[] suffix) {
    return combineTableNameSuffix(tableName, suffix);
  }
Creates a composite key to use as a mapper output key when using
MultiTableHFileOutputFormat.configureIncrementaLoad to set up bulk ingest job
@param tableName Name of the Table - Eg: TableName.getNameAsString()
@param suffix    Usually represents a rowkey when creating a mapper key or column family
@return byte[] representation of composite key
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/MultiTableHFileOutputFormat.java