protected boolean isBlockTerminationOK(Instruction instr) {
		return parallelHelper == null || parallelHelper.isEndOfParallelInstructionGroup(instr);
	}
Determine if {@link InstructionBlock} termination is allowed after the specified instruction
has been added.  Based upon the crossbuild requirements / parallel instruction semantics,
this method may return false to force continued fallthrough instruction accumulation within
the current block. 

@param instr last instruction disassembled
@return true if current block with last instruction may be terminated, false if block
must continue fallthrough instruction accumulation.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/disassemble/Disassembler.java