void activeProgram(Program program) {
		ProgramManager programManager = tool.getService(ProgramManager.class);
		programManager.setCurrentProgram(program);
	}
Get the second program for the current Diff.

@return the Diff's second program or null if don't currently have a second program associated
        for a Diff.
Ghidra/Features/ProgramDiff/src/main/java/ghidra/app/plugin/core/diff/ProgramDiffPlugin.java