code: protected static StringBuilder appendResourcePathPrefixFor(StringBuilder sb, String pkgName)
  	{
  		if(pkgName == null)
  			throw new NullPointerException("pkgName is null");
  		if(sb == null)
  			sb = new StringBuilder(pkgName.length() + 2);
  		sb.append('/');
  		if(pkgName.length() == 0)
  			return sb;
  		sb.append(pkgName.replace('.','/'));
  		pkgName = null;
  		sb.append('/');
  		return sb;
  	}
docs: Apend a package name converted to a resource path prefix.
  @param sb what to append to. If this is null, a new
  StringBuilder is created.
  @param pkgName The name of the package.
  @return Path, starting and ending with a slash, for resources
  prefixed by pkgName.
  @throws NullPointerException if pkgName is null.