code: public Class<?> getType(ELContext context,
                           Object base,
                           Object property) {
  
          if (context == null) {
              throw new NullPointerException();
          }
  
          if (base != null && base instanceof List) {
              context.setPropertyResolved(true);
              List list = (List) base;
              int index = toInteger(property);
              if (index < 0 || index >= list.size()) {
                  throw new PropertyNotFoundException();
              } 
              return Object.class;
          }
          return null;
      }
docs: If the base object is a list, returns the most general acceptable type
  for a value in this list.
  
  <p>If the base is a <code>List</code>, the <code>propertyResolved</code>
  property of the <code>ELContext</code> object must be set to
  <code>true</code> by this resolver, before returning. If this property
  is not <code>true</code> after this method is called, the caller
  should ignore the return value.</p>
  
  <p>Assuming the base is a <code>List</code>, this method will always
  return <code>Object.class</code>. This is because <code>List</code>s
  accept any object as an element.</p>
  
  @param context The context of this evaluation.
  @param base The list to analyze. Only bases of type <code>List</code>
  are handled by this resolver.
  @param property The index of the element in the list to return the
  acceptable type for. Will be coerced into an integer, but
  otherwise ignored by this resolver.
  @return If the <code>propertyResolved</code> property of
  <code>ELContext</code> was set to <code>true</code>, then
  the most general acceptable type; otherwise undefined.
  @throws PropertyNotFoundException if the given index is out of
  bounds for this list.
  @throws NullPointerException if context is <code>null</code>
  @throws ELException if an exception was thrown while performing
  the property or variable resolution. The thrown exception
  must be included as the cause property of this exception, if
  available.