public void setStartOfFlow(boolean isStart) {
		isStartOfFlow = isStart;
	}
Allows the block to be tagged as start of flow to force
InstructionSet iterator to treat as a flow start.
This method should not be used after this block has
been added to an InstructionSet
@param isStart
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/lang/InstructionBlock.java