title: Print when espression - check if is empty array
body: <p>In JasperReport I want to print a field when it does not contain empty array.</p>
  
  <p>How can I check it?</p>
  
  <p>In "Print when expression" it is possible to write:</p>
  
  <p>$F{myField} != null</p>
  
  <p>but as $F{myField} is an empty array (so it is not null) it does not work.</p>
  
  <p>Is there any method to check it? It seems to me that there is no isEmpty() function for JasperReport.</p>