A javax.swing.ImageIcon, where the supplied image details are loaded into the icon.
The value argument can be a String, URL, java.awt.Image, or byte. There is no attribute equivilent to the byte value argument.
If the value argument is a String it can be treated in multiple ways. If the value resolved to a File resolved without any context, then the value argument is treated as though it was passed in as a file: attribute. If the file does not exist, it is treated as though it were passed in as a resource: attribute.
the value argument, file :, url:, image:, and resource: are mutually exclusive.
//TODO we should accept strings to file: and url:, in the future.
imageIcon() is a leaf node, no child content is allowed.