Refactor: Clean up Sonar Lint issues

[felipestanzani]

Summary

Refactor classes to clean up Sonar Lint issues

Context

There are many code smells and possible improvements detected by Sonar Lint.

Task

Analyze the project files using Sonar Lint, mainly StatementServiceImpl, and implement the suggested fixes when possible.

Acceptance Criteria

• No complex or brain methods
• No unused import
• No unused variable
• No redundant code
• No code smell
• Code compiles successfully
• Existing tests pass
• No functional changes (pure refactoring)

[rrobetti]

@felipestanzani thanks for opening this issue.

[jenspapenhagen]

Start with the Test files:
#325