protected Object lookup(String jndiName) throws NamingException {
        return lookup(jndiName, null);
    }
Perform an actual JNDI lookup for the given name via the JndiTemplate.
<p>If the name doesn't begin with "java:comp/env/", this prefix is added
if "resourceRef" is set to "true".

@param jndiName the JNDI name to look up
@return the obtained object
@throws javax.naming.NamingException if the JNDI lookup failed
@see #setResourceRef
core/src/main/java/org/apache/shiro/jndi/JndiLocator.java