resolve comments, update getEventTypet test to become parameterized

Signed-off-by: Shenoy Pratik <sgguruda@amazon.com>

Author: ps48

data-prepper-expression/src/main/java/org/opensearch/dataprepper/expression/GetEventTypeExpressionFunction.java

@@ -19,7 +19,7 @@ public String getFunctionName() {
     }
 
     @Override
-    public Object evaluate(final List<Object> args, Event event, Function<Object, Object> convertLiteralType) {
+    public Object evaluate(final List<Object> args, final Event event, final Function<Object, Object> convertLiteralType) {
         if (!args.isEmpty()) {
             throw new RuntimeException("getEventType() does not take any arguments");
         }

data-prepper-expression/src/main/java/org/opensearch/dataprepper/expression/ParseTreeCoercionService.java

@@ -26,7 +26,7 @@ class ParseTreeCoercionService {
     @Inject
     public ParseTreeCoercionService(
             final Map<Class<? extends Serializable>, Function<Object, Object>> literalTypeConversions,
-            ExpressionFunctionProvider expressionFunctionProvider) {
+            final ExpressionFunctionProvider expressionFunctionProvider) {
         this.literalTypeConversions = literalTypeConversions;
         convertLiteralType = (value) -> {
             if (literalTypeConversions.containsKey(value.getClass())) {

data-prepper-expression/src/test/java/org/opensearch/dataprepper/expression/GetEventTypeExpressionFunctionTest.java

@@ -3,6 +3,9 @@
 import org.opensearch.dataprepper.model.event.Event;
 import org.opensearch.dataprepper.model.event.JacksonEvent;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
@@ -27,14 +30,15 @@ private Event createTestEvent(final String eventType) {
                 .build();
     }
 
-    @Test
-    void testGetEventTypeReturnsCorrectType() {
+    @ParameterizedTest
+    @ValueSource(strings = {"LOG", "TRACE", "METRIC"})
+    void testGetEventTypeReturnsCorrectType(String eventType) {
         GetEventTypeExpressionFunction function = createObjectUnderTest();
-        Event testEvent = createTestEvent("LOG");
+        Event testEvent = createTestEvent(eventType);
 
         Object result = function.evaluate(List.of(), testEvent, Function.identity());
 
-        assertThat(result, equalTo("LOG"));
+        assertThat(result, equalTo(eventType));
     }
 
     @Test