Add toString() for better resource debugging

[iloveeclipse]

See #470

[fedejeanne]

Could the calls to methods like exists() or isSet(int) become a bottleneck or are they mere bitwise comparisons?

[iloveeclipse]

It's toString(), which bottleneck you mean? It's only used while debugging code.

[fedejeanne]

I know, debugging is also a use-case for us developers, that's why I ask. Additionally, one can never completely rule out the possibility that production code is using toString() too (even if it's a bad idea).

Let me rephrase :-)
I've noticed that toString() now call methods as opposed to just reading from fields. I trust they will not (significantly) degrade performance, even when debugging? I can live with a slight performance decrease when debugging if it helps to debug.

[github-actions]

Test Results

   639 files  ±0     639 suites  ±0   38m 50s ⏱️ - 2m 28s
 3 949 tests ±0   3 927 ✅ ±0   22 💤 ±0  0 ❌ ±0 
12 453 runs  ±0  12 292 ✅ ±0  161 💤 ±0  0 ❌ ±0 

Results for commit 0d01b09. ± Comparison against base commit 1012283.

[iloveeclipse]

No, they don't degrade performance in a way anyone would notice that.

[iloveeclipse]

Test failis unrelated.