public byte[][] getPrefix() {
    int count = 0;
    byte[][] temp = new byte[sortedPrefixes.size()][];
    for (byte[] prefixes : sortedPrefixes) {
      temp[count++] = prefixes;
    }
    return temp;
  }
This filter is used for selecting only those keys with columns that matches a particular prefix.
For example, if prefix is 'an', it will pass keys will columns like 'and', 'anti' but not keys
with columns like 'ball', 'act'.
hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultipleColumnPrefixFilter.java