[Refactoring] Replace normal switches with enhanced switch expressions

[f-schnabel]

Purpose

Many existing switch statements are essentially simulations of switch expressions, where each arm either assigns to a common target variable or returns a value. Expressing this as a statement is roundabout, repetitive, and error-prone.

Java 14 added support for switch expressions, which provide more succinct and less error-prone version of switch. See also: https://sonarcloud.io/organizations/ballerina-platform/rules?languages=java&open=java%3AS5194&q=switch+expression Partly also fixes: https://sonarcloud.io/organizations/ballerina-platform/rules?open=java%3AS6208&rule_key=java%3AS6208

Approach

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Samples

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Remarks

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Check List

• [x] Read the Contributing Guide
• [ ] Updated Change Log
• [ ] Checked Tooling Support (#<Issue Number>)
• [ ] Added necessary tests
  • [ ] Unit Tests
  • [ ] Spec Conformance Tests
  • [ ] Integration Tests
  • [ ] Ballerina By Example Tests
• [ ] Increased Test Coverage
• [ ] Added necessary documentation
  • [ ] API documentation
  • [ ] Module documentation in Module.md files
  • [ ] Ballerina By Examples