Cave is a random generator based on game of life algorithm, now it is time to make another generator - that will generate map on basis of txt ASCII graphic schema.

Treasures need to somehow randomly draw item from pool, and place it in equipment

Start with trying to encapsulate recipe for a new lvl into some kind of class?

Such comparisions can be more meaningfull, by extracting logic to oneliner, but named method. It's easier to read and understand such code, as well as it speed up reading and finding the line we are interested in. It will be also visible on stack trace.
ex more meaningfull and undestandable comparisions:

        if (!withinHeightBoundaries(height)) {
            height = 25;
        }
        if (isNotWithinWithBoundaries(width)) {
            width = 100;
        }

https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/3ca3b69ece35b0ced4056e34e9183b11b9e4792e/src/main/java/data/terrains/Cave.java#L21

https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/3ca3b69ece35b0ced4056e34e9183b11b9e4792e/src/main/java/data/terrains/Cave.java#L24

Decided to resurrect this one, need people with good ideas :)

• use logger instead of STD out:
  https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/522f3941edf043fdddcd1beca2f38ba5db857908/src/test/java/data/equipment/EquipmentTest.java#L32

• there's .assertTrue https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/522f3941edf043fdddcd1beca2f38ba5db857908/src/test/java/data/equipment/EquipmentTest.java#L40

• when creating solider for test, you can encapsule it in more descriptive, and transferable method. Builder would also be more convenient.

Test will give false positives: https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/522f3941edf043fdddcd1beca2f38ba5db857908/src/test/java/data/equipment/EquipmentTest.java#L62

• according to other tests, there can be 4 items in equipment, you are reaching for 9th.
• you didn't check if adding and removing were successful. The equipment might been full or other items and didn't add, nor remove amour.
• Finally there's assertNull,

You can split by char: ' ', it will be faster.
https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/522f3941edf043fdddcd1beca2f38ba5db857908/src/test/java/data/equipment/EquipmentTest.java#L78

This test might give false negative:
https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/522f3941edf043fdddcd1beca2f38ba5db857908/src/test/java/data/equipment/EquipmentTest.java#L83
First assert, or make sure that there's expected number of HP. Then assert that healing potion added what it supposed to add. If you ever change default player HP, this will fail with false negative. You already set hp on line 10. it can be used again, in this test.
the same goes for last test useLargePotion

FightUtil seem to be a good place to start!

There is a tiny, little chance that randomly placed doors can cover the only access to the rest of the cave in location. Steping on doors means that you are changing location, so this could lead to cut off piece of a map.

Please don't log errors, as such:
https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/9ed1c8361e54fe0631ead8704d49db89ecc24d39/src/main/java/Main.java#L49
https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/9ed1c8361e54fe0631ead8704d49db89ecc24d39/src/main/java/locations/LocationsManager.java#L36
https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/9ed1c8361e54fe0631ead8704d49db89ecc24d39/src/main/java/data/equipment/bootstrap/ArmorStore.java#L36
and in: WeaponStore, CustomMap, LocationSaveUtil (twice)

Logger as a second parameter accepts Throwable, It's perfect for such occasions.

https://github.com/darkonion/RoguelikeGwiezdnaFlota/blob/3ca3b69ece35b0ced4056e34e9183b11b9e4792e/src/main/java/Main.java#L21

Thread sleep is a sign of code smell. It's working, but it's primitive and can be handeled in more modern way. Consider executor service and waiting for task that will be finished in new thread.