@Override
  public void start(CoprocessorEnvironment environment) {
    // make sure we are on a region server
    if (!(environment instanceof RegionCoprocessorEnvironment)) {
      throw new IllegalArgumentException(
        "Constraints only act on regions - started in an environment that was not a region");
    }
    RegionCoprocessorEnvironment env = (RegionCoprocessorEnvironment) environment;
    TableDescriptor desc = env.getRegion().getTableDescriptor();
    // load all the constraints from the HTD
    try {
      this.constraints = Constraints.getConstraints(desc, classloader);
    } catch (IOException e) {
      throw new IllegalArgumentException(e);
    }

    if (LOG.isInfoEnabled()) {
      LOG.info("Finished loading " + constraints.size() + " user Constraints on table: "
        + desc.getTableName());
    }

  }
Create the constraint processor.
<p>
Stores the current classloader.
hbase-server/src/main/java/org/apache/hadoop/hbase/constraint/ConstraintProcessor.java