code: private HTableDescriptor prepareTableDescriptor(String tableName,
        String entitySchemaString) {
      HTableDescriptor descriptor = new HTableDescriptor(
          Bytes.toBytes(tableName));
      AvroEntitySchema entitySchema = parser
          .parseEntitySchema(entitySchemaString);
      Set<String> familiesToAdd = entitySchema.getColumnMappingDescriptor()
          .getRequiredColumnFamilies();
      familiesToAdd.add(new String(Constants.SYS_COL_FAMILY));
      familiesToAdd.add(new String(Constants.OBSERVABLE_COL_FAMILY));
      for (String familyToAdd : familiesToAdd) {
        if (!descriptor.hasFamily(familyToAdd.getBytes())) {
          descriptor.addFamily(new HColumnDescriptor(familyToAdd));
        }
      }
      return descriptor;
    }
docs: Prepare the Table descriptor for the given entity Schema