public synchronized Object invoke()

in client/src/main/java/org/apache/qpid/client/PooledConnectionFactory.java [455:543]
85 lines of code
18 McCabe index (conditional complexity)

        public synchronized Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable
        {
            if(_closed)
            {
                throw new IllegalStateException("Connection is closed");
            }
            Method underlyingMethod = _underlyingConnection.getClass().getMethod(method.getName(), method.getParameterTypes());
            if(method.getName().equals("getExceptionListener"))
            {
                return _exceptionListener;
            }
            else if(method.getName().equals("setExceptionListener") && method.getParameterTypes().length == 1 && method.getParameterTypes()[0].equals(ExceptionListener.class))
            {
                _exceptionListener = (ExceptionListener) args[0];
                return null;
            }
            else if(method.getName().equals("close") && method.getParameterTypes().length == 0)
            {
                _closed = true;
                _exceptionListener = null;
                List<Session> openSessions = new ArrayList<>(_openSessions);
                for(Session session : openSessions)
                {
                    try
                    {
                        session.close();
                    }
                    catch(JMSException | RuntimeException | Error e)
                    {
                        _exceptionThrown = true;
                        try
                        {
                            _underlyingConnection.close();
                        }
                        finally
                        {
                            throw e;
                        }
                    }
                }
                _openSessions.clear();

                if(!_exceptionThrown)
                {
                    returnToPool(_underlyingConnection, _identityHash);
                }
                else
                {
                    _underlyingConnection.close();
                }

                return null;
            }
            else if(method.getName().equals("toString") && method.getParameterTypes().length == 0)
            {
                try
                {
                    Object returnVal = underlyingMethod.invoke(_underlyingConnection, args);
                    return "[Pool:"+_poolId+"][conn:"+_instanceId+"]: " + String.valueOf(returnVal);

                }
                catch (InvocationTargetException e)
                {
                    _exceptionThrown = true;
                    Throwable thrown = e.getCause();
                    throw thrown == null ? e : thrown;
                }
            }
            else
            {
                try
                {
                    Object returnVal = underlyingMethod.invoke(_underlyingConnection, args);

                    if(returnVal instanceof Session)
                    {
                        returnVal = proxySession((Session)returnVal, this);
                        _openSessions.add((Session)returnVal);
                    }
                    return returnVal;
                }
                catch (InvocationTargetException e)
                {
                    _exceptionThrown = true;
                    Throwable thrown = e.getCause();
                    throw thrown == null ? e : thrown;
                }
            }
        }