Fix spotbugs failures in java 17 migration

[dilanSachi]

Purpose

$subject

Examples

Checklist

• Linked to an issue
• Updated the changelog
• Added tests
• Updated the spec
• Checked native-image compatibility

[codecov]

Codecov Report

Patch coverage: 78.96% and project coverage change: -2.52% ⚠️

Comparison is base (5af1a74) 84.80% compared to head (565edc7) 82.28%.
Report is 17 commits behind head on java_17_migration.

Additional details and impacted files

@@                   Coverage Diff                   @@
##             java_17_migration      #10      +/-   ##
=======================================================
- Coverage                84.80%   82.28%   -2.52%     
- Complexity                  60      139      +79     
=======================================================
  Files                       14       24      +10     
  Lines                      408      717     +309     
  Branches                    62      126      +64     
=======================================================
+ Hits                       346      590     +244     
- Misses                      54       82      +28     
- Partials                     8       45      +37     

Files Changed	Coverage Δ
...rina/stdlib/mqtt/compiler/MqttDiagnosticCodes.java	0.00% <0.00%> (ø)
.../stdlib/mqtt/compiler/MqttServiceAnalysisTask.java	50.00% <50.00%> (ø)
...io/ballerina/stdlib/mqtt/compiler/PluginUtils.java	68.00% <68.00%> (ø)
.../compiler/MqttCodeTemplateWithCallerParameter.java	79.41% <79.41%> (ø)
...mpiler/MqttCodeTemplateWithoutCallerParameter.java	79.41% <79.41%> (ø)
...na/stdlib/mqtt/compiler/MqttFunctionValidator.java	80.80% <80.80%> (ø)
...ina/stdlib/mqtt/compiler/MqttServiceValidator.java	93.33% <93.33%> (ø)
...erina/stdlib/mqtt/compiler/MqttCompilerPlugin.java	100.00% <100.00%> (ø)
...rina/stdlib/mqtt/compiler/MqttServiceAnalyzer.java	100.00% <100.00%> (ø)
...allerina/stdlib/mqtt/compiler/PluginConstants.java	100.00% <100.00%> (ø)

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