feat: respect code guru profile handler implementation (#304)

Co-authored-by: Pankaj Agrawal <pankaagr@amazon.com>

Author: pankajagrawal16

powertools-core/src/main/java/software/amazon/lambda/powertools/core/internal/LambdaHandlerProcessor.java

@@ -36,7 +36,9 @@ private LambdaHandlerProcessor() {
     }
 
     public static boolean isHandlerMethod(final ProceedingJoinPoint pjp) {
-        return "handleRequest".equals(pjp.getSignature().getName());
+        return "handleRequest".equals(pjp.getSignature().getName()) ||
+                // https://docs.aws.amazon.com/codeguru/latest/profiler-ug/lambda-custom.html
+                "requestHandler".equals(pjp.getSignature().getName());
     }
 
     public static boolean placedOnRequestHandler(final ProceedingJoinPoint pjp) {

powertools-core/src/test/java/software/amazon/lambda/powertools/core/internal/LambdaHandlerProcessorTest.java

@@ -0,0 +1,45 @@
+package software.amazon.lambda.powertools.core.internal;
+
+import org.aspectj.lang.ProceedingJoinPoint;
+import org.aspectj.lang.Signature;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class LambdaHandlerProcessorTest {
+
+    @Test
+    void shouldTreatProfilerHandlerMethodAsValid() {
+        ProceedingJoinPoint pjpMock = mock(ProceedingJoinPoint.class);
+        Signature signature = mock(Signature.class);
+        when(signature.getName()).thenReturn("requestHandler");
+        when(pjpMock.getSignature()).thenReturn(signature);
+
+        assertThat(LambdaHandlerProcessor.isHandlerMethod(pjpMock))
+                .isTrue();
+    }
+
+    @Test
+    void shouldTreatDefaultHandlerMethodAsValid() {
+        ProceedingJoinPoint pjpMock = mock(ProceedingJoinPoint.class);
+        Signature signature = mock(Signature.class);
+        when(signature.getName()).thenReturn("handleRequest");
+        when(pjpMock.getSignature()).thenReturn(signature);
+
+        assertThat(LambdaHandlerProcessor.isHandlerMethod(pjpMock))
+                .isTrue();
+    }
+
+    @Test
+    void shouldNotTreatOtherMethodNamesAsValidHandlerMethod() {
+        ProceedingJoinPoint pjpMock = mock(ProceedingJoinPoint.class);
+        Signature signature = mock(Signature.class);
+        when(signature.getName()).thenReturn("handleRequestInvalid");
+        when(pjpMock.getSignature()).thenReturn(signature);
+
+        assertThat(LambdaHandlerProcessor.isHandlerMethod(pjpMock))
+                .isFalse();
+    }
+}