I have a field annotated like this: 

  @NotEmpty
  public String[] specializations;

When I do a POST request to: 

  @POST
  public Response post(@Valid Doctor body) {...}

with an empty array I get this:

  }}{{java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0

The cause is this line of code:  

https://github.com/resteasy/Resteasy/blob/87cd2f8413bf0914284faf4cbcd36dbbc838fdca/resteasy-core-spi/src/main/java/org/jboss/resteasy/api/validation/ResteasyViolationException.java#L363

 It assumes that the array is never empty.