@defaultMessage spawns threads with vague names; use a custom thread factory and name threads so that you can tell (by its name) which executor it is associated with
java.lang.Character#codePointBefore(char[],int) @ Implicit start offset is error-prone when the char[] is a buffer and the first chars are random chars
java.lang.Character#codePointAt(char[],int) @ Implicit end offset is error-prone when the char[] is a buffer and the last chars are random chars
@defaultMessage Collections.sort dumps data into an array, sorts the array and reinserts data into the list, one should rather use Lucene's CollectionUtil sort methods which sort in place