An iterator providing paginated access to JIRA REST services issue search results, in order to simplify 'maxResults' management. Every element is an iterator on the results of a single REST service call, hence obtaining ondemand fetches.

JiraIssueIterator.java

public class JiraIssuesIterator implements java.util.Iterator<java.util.Iterator<Issue>>{

    SearchRestClient searchClient
    int pageSize
    String jql
    Set<String> fields

    int startAt = 0
    int consumedIssuesCounter = 0
    int issueTotal

    SearchResult searchResult

    /**
     * the 1st hasNext() call should fetch data
     */
    protected boolean firstStep

    @Override
    public boolean hasNext() {
        if (searchResult==null) {
            firstStep = true
            search()
        }
        return consumedIssuesCounter < issueTotal;
    }

    @Override
    public Iterator<Issue> next() {
        if (firstStep) {
            firstStep = false
        } else {
            search()
        }
        Iterator<Issue> issues = searchResult.issues.iterator()

        return [
            hasNext:{ issues.hasNext() },
            next: {
                consumedIssuesCounter++
                issues.next()
            }
        ] as Iterator<Issue>
    }

    def search() {
        searchResult = searchClient.searchJql(jql, pageSize, startAt, fields).claim()
        issueTotal = searchResult.total
    }

    @Override
    public void remove() {
        throw new UnsupportedOperationException()
    }
}

UsageSnippet.groovy

...
    Iterable<Issue> getRestIssuesWithJQL (){
        final JiraRestClient restClient = ...
        SearchRestClient searchClient = restClient.getSearchClient ()
        Set<String> fields = ...

        //concatenates the iterators using Guava Iterators.concat(Iterator<Iterator>) logic
        return [iterator: {Iterators.concat(new JiraIssuesIterator (jql: jqlSearchExpr, pageSize: jiraPageSize, fields: fields, searchClient: searchClient))}] as Iterable<Issue>

    }
...