code: public static El properties(final Field submit, final Field retrieve)
     {
        return new ElProperties(new TypeBasedExpression(submit.getDeclaringClass(), submit.getName()),
                 new TypeBasedExpression(retrieve.getDeclaringClass(), retrieve.getName()));
     }
docs: Create a new EL Value binding using a single expression to submit and retrieve values. The specified property must
  either be public, or have a publicly defined getter/setter. Instead of an EL expression this method expects a
  {@link Field} argument. The EL expression will be automatically created at runtime.