@Override
  public boolean isNullable() {
    return false;
  }
A base-class for {@link DataType} implementations backed by protobuf. See {@link PBCell}.
<p/>
Notice that, in hbase we always uses our own shaded version of protobuf, but you are free to use
the original version of protobuf in your own project.
hbase-examples/src/main/java/org/apache/hadoop/hbase/types/PBType.java