I found several useful interfaces and symbols that are not stated in the documentation (O, *, #), e.g. at
https://forum.plantuml.net/6429/component-interface-documentation
or
https://forum.plantuml.net/?qa=1736/are-partial-lollipop-for-component-diagrams-supported
Can I see which symbols are available from the source code? If yes, could you point me to the file?
And is it possible to use custom sprites instead of a circle or rectangle at the beginning or end of an arrow on a box? Is it possible to use a sprite as a connector?