Many, many thanks to the Transmitter webextension.
This part of this plugin contains code which was adapted from the Transmitter webextension, which is a minimal interface to the transmission-rpc interfaces of many torrent clients, including for our purposes snark-rpc and BiglyBT.
Transmitter is released under the UNLICENSE. An original copy is available at this URL: https://github.com/myfreeweb/transmitter/blob/master/UNLICENSE
A copy has also been included in this directory.
One of the coolest things this extension is able to do is communicate with a transmission-rpc enabled torrent client. Since it's an I2P focused plugin, the default configuration is set up for use with the I2PSnark-RPC plugin created by zzz. Since Snark-RPC isn't part of the main Java I2P distribution, in order to do this you'll have to install the plugin. You can get a copy of it from inside of I2P here:
I also have a mirror of the package with each release of the webextension, reflecting the version in use in the webextension at the time of the release.
To install the plugin, go to http://127.0.0.1:7657/configplugins and scroll down to the section of the page where it says "Installation from URL" and paste the following URL:
http://stats.i2p/i2p/plugins/i2psnark-rpc.su3
Click the "Install Plugin" button and you'll be ready to go. Now, open the extension options menu, and just click "Save." The defaults are correct for use with I2PSnark-RPC, but they need to be initialized by saving the settings. If I2PSnark-RPC becomes part of Java I2P, these defaults will be initialized when the plugin is installed.