@Override
    public int getColumnFamilyCount() {
      return families.size();
    }
@param bytes A pb serialized {@link ModifyableTableDescriptor} instance with pb magic prefix
@return An instance of {@link ModifyableTableDescriptor} made from <code>bytes</code>
@see #toByteArray()
hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java