Help Center returns zero Confluence articles if payload exceeds 256 characters

Issue Summary

The Help Center within the Customer Portal of JSM project does not return any knowledge-base articles from Confluence when a high number of JSM projects are linked to unique Confluence spaces.

This is due to the API payload sent to the Confluence "knowledge-base/1.0/search" endpoint exceeding 256 characters which is the character limit set in Confluence. This is being tracked on the Confluence side in CONFSERVER-33174.

Steps to Reproduce

1. Link a Jira and Confluence instance using Application Links.
2. Create multiple Confluence spaces (keys: JSM1 - JSM13).
3. Create multiple JSM projects (keys: JSM1 - JSM13).
4. Link each of the individual JSM projects to their respective Confluence space within the Project Settings -> Knowledge base page, such as the JSM1 Jira project to the JSM1 Confluence space.
5. Navigate to /servicedesk/customer/portals
6. Perform a search with one of the Confluence space keys, such as jsm1.

Expected Results

Articles matching the query string are displayed on the main Help Center page.

Debug Logging (org.apache.http)

2021-12-22 13:20:02,189-0600 http-nio-48202-exec-11 DEBUG admin 800x1283x2 1x9w72o 0:0:0:0:0:0:0:1 /rest/servicedesk/knowledgebase/latest/articles/shared/search [o.a.h.impl.execchain.MainClientExec] Executing request GET /c7132/rest/knowledge-base/1.0/search?type=page&queryString=%28jsm2%29+AND+%28spacekey%3A%22JSM2%22+OR+spacekey%3A%22JSM1%22%29&pageSize=3&startIndex=0&highlight=true&xoauth_requestor_id=admin HTTP/1.1

Actual Results

No articles are displayed on the main Help Center page.

Debug Logging (org.apache.http)

2021-12-22 13:38:48,044-0600 http-nio-48202-exec-8 DEBUG admin 818x2061x2 1x9w72o 0:0:0:0:0:0:0:1 /rest/servicedesk/knowledgebase/latest/articles/shared/search [o.a.h.impl.execchain.MainClientExec] Executing request GET /c7132/rest/knowledge-base/1.0/search?type=page&queryString=%28jsm1%29+AND+%28spacekey%3A%22JSM81%22+OR+spacekey%3A%22JSM91%22+OR+spacekey%3A%22JSM2%22+OR+spacekey%3A%22JSM3%22+OR+spacekey%3A%22JSM1%22+OR+spacekey%3A%22JSM6%22+OR+spacekey%3A%22JSM131%22+OR+spacekey%3A%22JSM7%22+OR+spacekey%3A%22JSM4%22+OR+spacekey%3A%22JSM5%22+OR+spacekey%3A%22JSM101%22+OR+spacekey%3A%22JSM111%22+OR+spacekey%3A%22JSM121%22%29&pageSize=3&startIndex=0&highlight=true&xoauth_requestor_id=admin HTTP/1.1

Workaround

Due to the nature of the bug, the only workaround is to reduce the amount of unique spaces linked to each of the JSM projects until the query string is less than 256 characters.