Not to hard to create a Signal Mast from two signal heads, also not rocket science to create some Signal Mast Logic
, but what I can't figure out, is how to enable the "diverging" (or bottom) signal head to change color:
The "Panel" is shown on the right hand side, and when you throw the turnout, or activate the main line (bottom line) sensor, the top (left) green signal goes red. Close the turnout and/or inactivate the sensor and the Signal Mast cycles from red to yellow to green pretty quickly. But where do you tell JMRI to do something for the bottom signal head (right)?
Found the answer! You need to create a second Signal Mast Logic line (blue) that uses the signal in the siding as the "paired" Destination Mast:
Now we have all up and running. Also note the Red/Stop masts at the end of the lines to use as the Destination Mast: