Things to do on raising min supported API level

[moving-bits]

Currently c:geo supports API level 21+ (which is Android 5), which means that some features or package upgrades are blocked. To keep in mind what can be done and/or needs to be done when raising the minimum supported API level, let's collect those items here. Feel free to add to this list.

(min API 24)

• update apache.commons.lang (and unblock from dependabot)

(min API 26)

• update apache.commons.compress (and unblock from dependabot)
• update commons-io:commons-io (and unblock from dependabot)
• update org.apache.commons:commons-text (and unblock from dependabot)
• update com.fasterxml.jackson.* (and unblock from dependabot)

[Lineflyer]

BTW:
I guess we can/should raise rather soon to API 26 and revive the legacy version for supporting <26 a bit longer.

[moving-bits]

AFAIK there are no functional limitations and no security problems related to the two Apache libs not having the most recent version (@bekuno?), so it's probably easier for us to stay with min supported API level 21 for now, as maintaining two deliverables and cross-patching things would be more work for us.

This might change immediately, though, if any real "blocker" comes up, either feature-, security- or architecture-wise. That's the main reason why I created this issue here, to collect such things and to be able to do an active decision for raising the min level at some point in time.