fix: usage of Optional.orElseThrow after Map.put

[artlomako]

Change list

• fix broken KeyEvent

Types of changes

What types of changes are you proposing/introducing to Java client? Put an x in the boxes that apply

• [ ] No changes in production code.
• [x] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Details

After the last change in KeyEvent class, it's impossible to use the key event, because the following code always throws an exception:

  ofNullable(this.keyCode)
                    .map(x -> map.put("keycode", x))
                    .orElseThrow(() -> new IllegalStateException("The key code must be set"));

since map.put() returns null for new key.

[linux-foundation-easycla[bot]]

The committers listed above are authorized under a signed CLA.

• :white_check_mark: login: artlomako / name: Artur Lomako (31a92790bebbd3ba09ea36fc2b01a1e5442ed169, 7806c7d356453643cb03c855b33c3745fb040d7b, dfdd24f6a78e0f4473fd51157f0388bcc37fea90)
• :white_check_mark: login: valfirst / name: Valery Yatsynovich (5ecd06a5f250ead4aa672a804175f668fba7ba5a, 9a19742536700d04a65f394817e7f24e3fb0690d, c55d0a80c9e60a789774ce4e528cd4284f54ef2b)

[valfirst]

@artlomako checkstyle is failed