[improve][build] Upgrade Spotbugs to a version with JDK 17 compatibility

[lhotari]

Motivation

Build log contains warning messages such as

(file:/home/runner/.m2/repository/com/github/spotbugs/spotbugs/4.2.2/spotbugs-4.2.2.jar)
     [java] WARNING: Please consider reporting this to the maintainers of edu.umd.cs.findbugs.ba.jsr305.TypeQualifierValue
     [java] WARNING: System::setSecurityManager will be removed in a future release
     [java] WARNING: A terminally deprecated method in java.lang.System has been called
     [java] WARNING: System::setSecurityManager has been called by edu.umd.cs.findbugs.ba.jsr305.TypeQualifierValue

This is fixed by spotbugs/spotbugs#1983 in 4.7.0

Modifications

Upgrade Spotbugs to 4.7.3.

Spotbugs 4.7.3 release notes:
https://github.com/spotbugs/spotbugs/releases/tag/4.7.3

Ignore violations in existing code that fail with new rules that are active in upgraded Spotbugs version.

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[lhotari]

Adding a comment here so that we have some documentation about handling EI_EXPOSE_REP Spotbugs errors.

This is the spotbugs description for EI_EXPOSE_REP

EI: May expose internal representation by returning reference to mutable object (EI_EXPOSE_REP)
Returning a reference to a mutable object value stored in one of the object's fields exposes the internal representation of the object. If instances are accessed by untrusted code, and unchecked changes to the mutable object would compromise security or other important properties, you will need to do something different. Returning a new copy of the object is better approach in many situations.

Newer versions of Spotbugs enable this rule by default. One possibility is to ignore the error.

There are 2 ways to ignore the error: with an annotation or with an XML file. Since there was a lot of locations where this is happening, I used the XML file in this PR. Having the rule is useful since we should be thinking of the implications of thread safety and so on when a mutable object is shared.