Consider returning a zero length array rather than null.

[Kui-Liu]

It is often a better design to return a length zero array rather than a null reference to indicate that there are no results (i.e., an empty list of results). This way, no explicit check for null is needed by clients of the method. On the other hand, using null to indicate "there is no answer to this question" is probably appropriate. http://findbugs.sourceforge.net/bugDescriptions.html#PZLA_PREFER_ZERO_LENGTH_ARRAYS

[coveralls]

Coverage remained the same at 89.963% when pulling 85a6eccec4822d142a4dec0ba369287e74de5ce4 on BruceKuiLiu:master3 into eafb16c711d5cd79edad5fbb2055252acdb3825e on apache:master.