code: public static OgnlEvaluator getInstance(final Object root, final String expression)
  	{
  		final OgnlEvaluatorCollection collection = INSTANCE.getEvaluators(getRootClass(root));
  
  		return collection.get(expression);
  	}
docs: Get an OGNL Evaluator for a particular expression with a given input
  
  @param root
  an example instance of the root object that will be passed to this OGNL evaluator
  @param expression
  the OGNL expression
  
  @return
  
  @see <a href="https://commons.apache.org/proper/commons-ognl/language-guide.html">OGNL Language Guide</a>