[Refactoring] Use try with resources to properly close resources

[f-schnabel]

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Purpose

Many resources in Java need be closed after they have been used. If they are not, the garbage collector cannot reclaim the resources' memory, and they are still considered to be in use by the operating system. Such resources are considered to be leaked, which can lead to performance issues.

Java 7 introduced the try-with-resources statement, which guarantees that the resource in question will be closed.

try (InputStream input = Files.newInputStream(path)) {
  // "input" will be closed after the execution of this block
}

This syntax is safer than the traditional method using try, catch, and finally and hence should be preferred.

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