public  void checkTld(String checkedTld) throws Exception 
{
        List tagsAttributes = getTagAttributeList(checkedTld);
        List errors = new ArrayList();
        Iterator iterator = tagsAttributes.iterator();
        while (iterator.hasNext())
        {
            TagAttribute attribute = (TagAttribute) iterator.next();
            if (log.isDebugEnabled())
            {
                log.debug("testing " + attribute);
            }
            String className = attribute.getTagClass();
            Class tagClass = null;
            try
            {
                tagClass = Class.forName(className);
            }
            catch (ClassNotFoundException e)
            {
                errors.add("unable to find declared tag class [" + className + "]");
                continue;
            }
            if (!TagSupport.class.isAssignableFrom(tagClass))
            {
                errors.add("Declared class [" + className + "] doesn't extend TagSupport");
                continue;
            }
            // load it
            Object tagObject = null;
            try
            {
                tagObject = tagClass.newInstance();
            }
            catch (Throwable e)
            {
                errors.add("unable to instantiate declared tag class [" + className + "]");
                continue;
            }
            if (!PropertyUtils.isWriteable(tagObject, attribute.getAttributeName()))
            {
                errors.add("Setter for attribute [" + attribute.getAttributeName() + "] not found in " + className);
                continue;
            }
            Class propertyType = PropertyUtils.getPropertyType(tagObject, attribute.getAttributeName());
            String tldType = attribute.getAttributeType();
            if (tldType != null)
            {
                Class tldTypeClass = getClassFromName(tldType);
                if (!propertyType.isAssignableFrom(tldTypeClass))
                {
                    errors.add("Tag attribute ["
                        + attribute.getAttributeName()
                        + "] declared in tld as ["
                        + tldType
                        + "], class declare ["
                        + propertyType.getName()
                        + "]");
                    continue;
                }
            }
        }
        if (errors.size()  > 0)
        {
            if (log.isInfoEnabled())
            {
                log.info(errors.size() + " errors found in tag classes: " + errors);
            }
            fail(errors.size() + " errors found in tag classes: " + errors);
        }
}

Check the given tld. Assure then:
• Any tag class is loadable
• the tag class has a setter for any of the declared attribute
• the type declared in the dtd for an attribute (if any) matches the type accepted by the getter

 public String getName() 
{
           
        return getClass().getName() + "." + super.getName();
}

 public  void testELTld() throws Exception 
{
        checkTld("/src/main/resources/META-INF/displaytag-el.tld");
}

Check displaytag EL dtd.

 public  void testStandardTld() throws Exception 
{
        checkTld("/src/main/resources/META-INF/displaytag.tld");
}

Check displaytag 1.2 dtd.