public void setBucketMatcherClass(
      Class<? extends BucketMatcher> bucketMatcherClass) {
    this.bucketMatcherClass = bucketMatcherClass;
  }
was inner class of MapreLocalWork. context for bucket mapjoin (or smb join)
ql/src/java/org/apache/hadoop/hive/ql/plan/BucketMapJoinContext.java