code: protected Object getDefaultValue(String propName, Class<?> returnType)
  	{
  		Object ret = null;
  		if(returnType.isPrimitive())
  		{
  			if(returnType.equals(boolean.class))
  			{
  				return false;
  			}
  			else if(returnType.equals(char.class))
  			{
  				return '\0';
  			}
  			else
  			{
  				try
  				{
  					Class<?> wrapperClass = Primitives.wrap(returnType);
  					return wrapperClass.getMethod("valueOf", String.class).invoke(null, "0");
  				} catch (Throwable e)
  				{
  					throw new WicketRuntimeException("Can't create default value for '"+propName+"' which should have type '"+returnType.getName()+"'");
  				} 
  			}
  		}
  		return ret;
  	}
docs: Method for obtaining default value of required property
  @param propName name of a property
  @param returnType type of a property
  @return default value for particular property