A NullPointerException means that one of the variables you are passing is null, but the code tries to use it like it is not.
For example, If I do this:
Integer myInteger = null;
int n = myInteger.intValue();
The code tries to grab the intValue of myInteger, but since it is null, it does not have one: a null pointer exception happens.
What this means is that your getTask method is expecting something that is not a null, but you are passing a null. Figure out what getTask needs and pass what it wants!