build(deps): bump com.github.spotbugs:spotbugs-maven-plugin from 4.8.…

…3.1 to 4.8.6.6 (#527)

* build(deps): bump com.github.spotbugs:spotbugs-maven-plugin

Bumps [com.github.spotbugs:spotbugs-maven-plugin](https://github.com/spotbugs/spotbugs-maven-plugin) from 4.8.3.1 to 4.8.6.6.
- [Release notes](https://github.com/spotbugs/spotbugs-maven-plugin/releases)
- [Commits](spotbugs/spotbugs-maven-plugin@spotbugs-maven-plugin-4.8.3.1...spotbugs-maven-plugin-4.8.6.6)

---
updated-dependencies:
- dependency-name: com.github.spotbugs:spotbugs-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

* Fix singleton in PerconaConstraintsService

---------

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Andreas Dangel <[email protected]>

pom.xml

@@ -201,7 +201,7 @@
                 <plugin>
                     <groupId>com.github.spotbugs</groupId>
                     <artifactId>spotbugs-maven-plugin</artifactId>
-                    <version>4.8.3.1</version>
+                    <version>4.8.6.6</version>
                     <configuration>
                         <excludeFilterFile>spotbugs-exclusions.xml</excludeFilterFile>
                     </configuration>

src/main/java/liquibase/ext/percona/PerconaConstraintsService.java

@@ -31,12 +31,16 @@
 import liquibase.structure.core.Table;
 
 public class PerconaConstraintsService {
-    private static PerconaConstraintsService instance = new PerconaConstraintsService();
+    private static final PerconaConstraintsService INSTANCE = new PerconaConstraintsService();
     private Logger log = Scope.getCurrentScope().getLog(PerconaConstraintsService.class);
     private boolean enabled = true;
 
+    private PerconaConstraintsService() {
+        // private constructor to prevent instantiation from somewhere else
+    }
+
     public static PerconaConstraintsService getInstance() {
-        return instance;
+        return INSTANCE;
     }
 
     /**