Gabe Stanek

**Describe the bug** We see occasional `NullPointerException`s propagated out of the `recurly-client-java`. The relevant observed stack trace is: ``` java.util.concurrent.ExecutionException: java.lang.NullPointerException: Cannot invoke "com.recurly.v3.Pager.getNext()" because "pager" is null at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122)...