Messages that need creating:

• apihelp-collection+addarticle-param-namespace
• apihelp-collection+addarticle-param-title
• apihelp-collection+addarticle-param-oldid
• apihelp-collection+addcategory-param-title
• apihelp-collection+addchapter-param-chaptername
• apihelp-collection+getbookcreatorboxcontent-param-hint
• apihelp-collection+getbookcreatorboxcontent-param-oldid
• apihelp-collection+getbookcreatorboxcontent-param-pagename
• apihelp-collection+getpopupdata-param-title
• apihelp-collection+postcollection-param-collection
• apihelp-collection+removearticle-param-namespace
• apihelp-collection+removearticle-param-title
• apihelp-collection+removeitem-param-index
• apihelp-collection+renamechapter-param-index
• apihelp-collection+renamechapter-param-chaptername
• apihelp-collection+settitles-param-title
• apihelp-collection+settitles-param-subtitle
• apihelp-collection+settitles-param-settings
• apihelp-collection+suggestarticleaction-param-title
• apihelp-collection+suggestundoarticleaction-param-title

Shown on https://en.wikipedia.org/w/api.php?modules=collection&recursivesubmodules=