#vulnerable code 
                                public boolean canPersistence() {
        return bifurcateProcessor.getLongestChain().size()> PocConsensusConstant.CONFIRM_BLOCK_COUNT;
    } 
                            #location 2 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public boolean canPersistence() {

        return null != bifurcateProcessor.getLongestChain() && bifurcateProcessor.getLongestChain().size() > PocConsensusConstant.CONFIRM_BLOCK_COUNT;
    }