Complex JQL including linkedissues and Epic link throws out 500 Error

Issue Summary
Complex JQL including linkedissues and Epic link throws out 500 Error

Steps to Reproduce

1. Create an agile project (Let's called it project A) and board.
2. Create at least two issues (A-1 and A-2) in the project
3. Link those issues together using issue link
4. Create an Epic
5. Insert those two issues into the newly created Epic
6. Create a filter as follows: {{Project = A and "Epic Link" in (linkedissues("A-1")) }}
7. Go to manage filter
8. Click on the newly created filter

Expected Result

• The filter would work as expected

Actual Result

• An error 500 is thrown. The following shows on the logs:

  java.lang.NullPointerException
  java.lang.NullPointerException
  	at com.atlassian.greenhopper.customfield.epiclink.EpicLinkSearchInputTransformer.computeOperandsFromSearchValues(EpicLinkSearchInputTransformer.java:126) [?:?]
  	at com.atlassian.greenhopper.customfield.epiclink.EpicLinkSearchInputTransformer.getClauseFromParams(EpicLinkSearchInputTransformer.java:102) [?:?]
  	at com.atlassian.jira.issue.customfields.searchers.transformer.AbstractCustomFieldSearchInputTransformer.getSearchClause(AbstractCustomFieldSearchInputTransformer.java:76) [jira-api-7.0.0-OD-01-193.jar:?]
  	at com.atlassian.jira.components.query.DefaultSearcherService.generateQuery(DefaultSearcherService.java:294) [?:?]
  	at com.atlassian.jira.components.query.DefaultSearcherService.searchWithJql(DefaultSearcherService.java:173) [?:?]
  	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [?:1.8.0_45]
  	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) [?:1.8.0_45]
  	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [?:1.8.0_45]
  	at java.lang.reflect.Method.invoke(Method.java:497) [?:1.8.0_45]
  	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317) [spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
  	at org.eclipse.gemini.blueprint.service.importer.support.internal.aop.ServiceInvoker.doInvoke(ServiceInvoker.java:56) [?:?]
  	at org.eclipse.gemini.blueprint.service.importer.support.internal.aop.ServiceInvoker.invoke(ServiceInvoker.java:60) [?:?]
  	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]