#vulnerable code 
                                public void shutdown() {
        this.shutdown = true;
        synchronized (this) {
            try {
                if (this.poolEntry != null) {
                    this.poolEntry.close();
                }
            } finally {
                this.poolEntry = null;
                this.conn = null;
            }
        }
    } 
                            #location 2 
                            #vulnerability type UNSAFE_GUARDED_BY_ACCESS
#fixed code
                                public void shutdown() {
        synchronized (this) {
            this.shutdown = true;
            try {
                if (this.poolEntry != null) {
                    this.poolEntry.close();
                }
            } finally {
                this.poolEntry = null;
                this.conn = null;
            }
        }
    }