BAEL 7138 Difference between String and StringBuffer in Java (#15351)

* string vs stringBuffer comparison

* BAEL-7138 Difference between String and StringBuffer in Java

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Co-authored-by: Sahil <sahilsriv05@gmail.com>

core-java-modules/core-java-strings/src/main/java/com/baeldung/stringbuffer/ComparePerformance.java

@@ -28,6 +28,7 @@ public class ComparePerformance {
 
     @Benchmark
     public String benchmarkStringConcatenation() {
+        strFinal = "";
         strFinal += strInitial;
         return strFinal;
     }