Describe the PR

This originated from #1932 and merged the test cases in InefficientStringBuffering.

Example false-negative, that is fixed:

String someString = getSomeString();
StringBuilder sb = new StringBuilder();
sb.append("a" + someString + "b"); // bad - false negative
sb.append('a').append(someString).append('b'); // good

Note: This also fixes a false-negative with AppendCharacterWithChar:

StringBuilder sb = new StringBuilder(message).append("\n");

https://github.com/spring-projects/spring-framework/tree/v5.0.6.RELEASE/spring-context/src/main/java/org/springframework/context/event/ApplicationListenerMethodAdapter.java#L308

Related issues

• Refs [java] Added 4 performance rules originating from PMD-jPinpoint-rules #1932 - this is the last PR from 1932

Ready?

• Fix false positive in InefficientStringBuffering with ternary expression: https://github.com/spring-projects/spring-framework/blob/v5.0.6.RELEASE/spring-core/src/main/java/org/springframework/util/backoff/ExponentialBackOff.java#L222
• Fix false positive in AppendCharacterWithChar for constructors: https://github.com/spring-projects/spring-framework/blob/v5.0.6.RELEASE/spring-expression/src/main/java/org/springframework/expression/spel/ast/FunctionReference.java#L145
• Update release notes - mention this PR under fixed issues
• Add deprecation notice for InefficientStringBuffering::isInStringBufferOperation
• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by travis)
• Added (in-code) documentation (if needed)