[Task] Clean up Spotbugs deficiencies or suppress

[andrewazores]

#112 turned on Spotbugs, which reveals that there are several potential problem areas identified already:

https://github.com/cryostatio/cryostat3/actions/runs/6579676143/job/17876067218#step:15:1595

[INFO] --- spotbugs:4.7.3.6:check (spotbugs) @ cryostat3 ---
[INFO] BugInstance size is 34
[INFO] Error size is 0
[INFO] Total bugs: 34
Error:  Medium: Dead store to pod in io.cryostat.discovery.ContainerDiscovery.handleContainerEvent(ContainerDiscovery$ContainerSpec, Target$EventKind) [io.cryostat.discovery.ContainerDiscovery] At ContainerDiscovery.java:[line 341] DLS_DEAD_LOCAL_STORE
Error:  High: io.cryostat.discovery.DiscoveryNode.NODE_TYPE isn't final but should be [io.cryostat.discovery.DiscoveryNode] At DiscoveryNode.java:[line 58] MS_SHOULD_BE_FINAL
Error:  High: io.cryostat.discovery.DiscoveryNode.POD isn't final but should be [io.cryostat.discovery.DiscoveryNode] At DiscoveryNode.java:[line 61] MS_SHOULD_BE_FINAL
Error:  High: io.cryostat.discovery.DiscoveryNode.REALM isn't final but should be [io.cryostat.discovery.DiscoveryNode] At DiscoveryNode.java:[line 60] MS_SHOULD_BE_FINAL
Error:  High: io.cryostat.discovery.DiscoveryNode.UNIVERSE isn't final but should be [io.cryostat.discovery.DiscoveryNode] At DiscoveryNode.java:[line 59] MS_SHOULD_BE_FINAL
Error:  High: Method io.cryostat.discovery.DiscoveryNode$Listener.onMessage(Target$TargetDiscovery) seems to be useless [io.cryostat.discovery.DiscoveryNode$Listener] At DiscoveryNode.java:[line 167] UC_USELESS_VOID_METHOD
Error:  High: Found reliance on default encoding in io.cryostat.discovery.DiscoveryPlugin$PluginCallback$AuthorizationFilter.filter(ClientRequestContext): String.getBytes() [io.cryostat.discovery.DiscoveryPlugin$PluginCallback$AuthorizationFilter] At DiscoveryPlugin.java:[line 145] DM_DEFAULT_ENCODING
Error:  High: Null pointer dereference of credential in io.cryostat.discovery.DiscoveryPlugin$PluginCallback$AuthorizationFilter.filter(ClientRequestContext) [io.cryostat.discovery.DiscoveryPlugin$PluginCallback$AuthorizationFilter] Dereferenced at DiscoveryPlugin.java:[line 140] NP_ALWAYS_NULL
Error:  Medium: io.cryostat.events.SerializableEventTypeInfo.category() may expose internal representation by returning SerializableEventTypeInfo.category [io.cryostat.events.SerializableEventTypeInfo] At SerializableEventTypeInfo.java:[line 26] EI_EXPOSE_REP
Error:  Medium: io.cryostat.events.SerializableEventTypeInfo.options() may expose internal representation by returning SerializableEventTypeInfo.options [io.cryostat.events.SerializableEventTypeInfo] At SerializableEventTypeInfo.java:[line 26] EI_EXPOSE_REP
Error:  Medium: io.cryostat.expressions.MatchExpression$ExpressionEvent.expression() may expose internal representation by returning MatchExpression$ExpressionEvent.expression [io.cryostat.expressions.MatchExpression$ExpressionEvent] At MatchExpression.java:[line 148] EI_EXPOSE_REP
Error:  Medium: new io.cryostat.expressions.MatchExpression$ExpressionEvent(MatchExpression$ExpressionEventCategory, MatchExpression) may expose internal representation by storing an externally mutable object into MatchExpression$ExpressionEvent.expression [io.cryostat.expressions.MatchExpression$ExpressionEvent] At MatchExpression.java:[line 149] EI_EXPOSE_REP2
Error:  Medium: io.cryostat.expressions.MatchExpression$MatchedExpression.targets() may expose internal representation by returning MatchExpression$MatchedExpression.targets [io.cryostat.expressions.MatchExpression$MatchedExpression] At MatchExpression.java:[line 92] EI_EXPOSE_REP
Error:  Medium: new io.cryostat.expressions.MatchExpression$MatchedExpression(Long, String, Collection) may expose internal representation by storing an externally mutable object into MatchExpression$MatchedExpression.targets [io.cryostat.expressions.MatchExpression$MatchedExpression] At MatchExpression.java:[line 94] EI_EXPOSE_REP2
Error:  Medium: Unread field: io.cryostat.expressions.MatchExpressionEvaluator$MatchExpressionAppliesEvent.matchExpression [io.cryostat.expressions.MatchExpressionEvaluator$MatchExpressionAppliesEvent] At MatchExpressionEvaluator.java:[line 183] URF_UNREAD_FIELD
Error:  Medium: io.cryostat.recordings.EventOptionsBuilder.build() may expose internal representation by returning EventOptionsBuilder.map [io.cryostat.recordings.EventOptionsBuilder] At EventOptionsBuilder.java:[line 90] EI_EXPOSE_REP
Error:  High: Found reliance on default encoding in io.cryostat.recordings.RecordingHelper.createMetadataTagging(Recordings$Metadata): String.getBytes() [io.cryostat.recordings.RecordingHelper] At RecordingHelper.java:[line 626] DM_DEFAULT_ENCODING
Error:  High: Found reliance on default encoding in io.cryostat.recordings.RecordingHelper.lambda$createMetadataTagging$9(Map$Entry): String.getBytes() [io.cryostat.recordings.RecordingHelper, io.cryostat.recordings.RecordingHelper] At RecordingHelper.java:[line 611]Another occurrence at RecordingHelper.java:[line 614] DM_DEFAULT_ENCODING
Error:  Medium: Unread field: io.cryostat.recordings.RecordingHelper.httpTimeoutSeconds; should this field be static? [io.cryostat.recordings.RecordingHelper] At RecordingHelper.java:[line 112] SS_SHOULD_BE_STATIC
Error:  High: Found reliance on default encoding in io.cryostat.recordings.Recordings.lambda$createMetadataTagging$33(Map$Entry): String.getBytes() [io.cryostat.recordings.Recordings, io.cryostat.recordings.Recordings] At Recordings.java:[line 852]Another occurrence at Recordings.java:[line 855] DM_DEFAULT_ENCODING
Error:  Medium: io.cryostat.recordings.Recordings$ArchivedRecordingDirectory.recordings() may expose internal representation by returning Recordings$ArchivedRecordingDirectory.recordings [io.cryostat.recordings.Recordings$ArchivedRecordingDirectory] At Recordings.java:[line 957] EI_EXPOSE_REP
Error:  Medium: io.cryostat.recordings.Recordings$Metadata.labels() may expose internal representation by returning Recordings$Metadata.labels [io.cryostat.recordings.Recordings$Metadata] At Recordings.java:[line 968] EI_EXPOSE_REP
Error:  Medium: new io.cryostat.recordings.Recordings$Metadata(Map, Instant) may expose internal representation by storing an externally mutable object into Recordings$Metadata.labels [io.cryostat.recordings.Recordings$Metadata] At Recordings.java:[line 969] EI_EXPOSE_REP2
Error:  Medium: Unread public/protected field: io.cryostat.rules.Rule.description [io.cryostat.rules.Rules] At Rules.java:[line 120] URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD
Error:  Medium: io.cryostat.rules.Rule$RuleEvent.rule() may expose internal representation by returning Rule$RuleEvent.rule [io.cryostat.rules.Rule$RuleEvent] At Rule.java:[line 124] EI_EXPOSE_REP
Error:  Medium: new io.cryostat.rules.Rule$RuleEvent(Rule$RuleEventCategory, Rule) may expose internal representation by storing an externally mutable object into Rule$RuleEvent.rule [io.cryostat.rules.Rule$RuleEvent] At Rule.java:[line 125] EI_EXPOSE_REP2
Error:  Medium: io.cryostat.rules.RuleService$RuleRecording.recording() may expose internal representation by returning RuleService$RuleRecording.recording [io.cryostat.rules.RuleService$RuleRecording] At RuleService.java:[line 284] EI_EXPOSE_REP
Error:  Medium: io.cryostat.rules.RuleService$RuleRecording.rule() may expose internal representation by returning RuleService$RuleRecording.rule [io.cryostat.rules.RuleService$RuleRecording] At RuleService.java:[line 284] EI_EXPOSE_REP
Error:  Medium: new io.cryostat.rules.RuleService$RuleRecording(Rule, ActiveRecording) may expose internal representation by storing an externally mutable object into RuleService$RuleRecording.recording [io.cryostat.rules.RuleService$RuleRecording] At RuleService.java:[line 285] EI_EXPOSE_REP2
Error:  Medium: new io.cryostat.rules.RuleService$RuleRecording(Rule, ActiveRecording) may expose internal representation by storing an externally mutable object into RuleService$RuleRecording.rule [io.cryostat.rules.RuleService$RuleRecording] At RuleService.java:[line 285] EI_EXPOSE_REP2
Error:  Medium: io.cryostat.targets.Target$Annotations.cryostat() may expose internal representation by returning Target$Annotations.cryostat [io.cryostat.targets.Target$Annotations] At Target.java:[line 128] EI_EXPOSE_REP
Error:  Medium: io.cryostat.targets.Target$Annotations.platform() may expose internal representation by returning Target$Annotations.platform [io.cryostat.targets.Target$Annotations] At Target.java:[line 128] EI_EXPOSE_REP
Error:  Medium: io.cryostat.targets.Target$TargetDiscovery.serviceRef() may expose internal representation by returning Target$TargetDiscovery.serviceRef [io.cryostat.targets.Target$TargetDiscovery] At Target.java:[line 174] EI_EXPOSE_REP
Error:  Medium: new io.cryostat.targets.Target$TargetDiscovery(Target$EventKind, Target) may expose internal representation by storing an externally mutable object into Target$TargetDiscovery.serviceRef [io.cryostat.targets.Target$TargetDiscovery] At Target.java:[line 175] EI_EXPOSE_REP2
[INFO] 


To see bug detail using the Spotbugs GUI, use the following command "mvn spotbugs:gui"



[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  04:45 min
[INFO] Finished at: 2023-10-19T20:13:21Z
[INFO] ------------------------------------------------------------------------
Error:  Failed to execute goal com.github.spotbugs:spotbugs-maven-plugin:4.7.3.6:check (spotbugs) on project cryostat3: failed with 34 bugs and 0 errors -> [Help 1]

Each of these should be checked and either corrected (the Spotbugs error code can be referenced against the bug descriptions list for potential resolutions), or if it is a false positive then @SuppressFBWarnings can be added to suppress the warning and allow the CI to pass.