#vulnerable code 
                             @Test
	public void shouldCreateConversation() throws Exception {
		// given
		MessageMatcher matcher = new MessageMatcher();
		InternalMessage message = InternalMessage.create()//
				.from(Member.builder()//
						.session(mockSession("sessionId", matcher))//
						.build())//
				.signal(create)//
				.content("c1")//
				.build();

		// when
		create.executeMessage(message);

		// then
		Optional<Conversation> conv = conversations.findBy("c1");
		assertTrue(conv.isPresent());
		Message send = matcher.getMessage();
		assertNotNull(send);
		assertThat(send.getFrom(), is(EMPTY));
		assertThat(send.getTo(), is("sessionId"));
		assertThat(send.getSignal(), is("created"));
		assertThat(send.getContent(), is("c1"));
		assertThat(send.getParameters(), notNullValue());
	} 
                            #location 21 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             @Test
	public void shouldCreateConversation() throws Exception {
		// given
		MessageMatcher matcher = new MessageMatcher();
		InternalMessage message = InternalMessage.create()//
				.from(Member.create()//
						.session(mockSession("sessionId", matcher))//
						.build())//
				.signal(create)//
				.content("c1")//
				.build();

		// when
		create.executeMessage(message);

		// then
		Optional<Conversation> conv = conversations.findBy("c1");
		assertTrue(conv.isPresent());
		Message send = matcher.getMessage();
		assertNotNull(send);
		assertThat(send.getFrom(), is(EMPTY));
		assertThat(send.getTo(), is("sessionId"));
		assertThat(send.getSignal(), is("created"));
		assertThat(send.getContent(), is("c1"));
		assertThat(send.getParameters(), notNullValue());
	}