exception messages detailed

Author: jeromevdl

powertools-serialization/src/main/java/software/amazon/lambda/powertools/utilities/EventDeserializer.java

@@ -188,7 +188,7 @@ public <T> T as(Class<T> clazz) {
                     throw new EventDeserializationException("The content of this event is a list, consider using 'asListOf' instead");
                 }
                 // should not occur, except if the event is malformed (missing fields)
-                throw new IllegalStateException("Event content is null");
+                throw new IllegalStateException("Event content is null: the event may be malformed (missing fields)");
             } catch (IOException e) {
                 throw new EventDeserializationException("Cannot load the event as " + clazz.getSimpleName(), e);
             }
@@ -206,7 +206,7 @@ public <T> List<T> asListOf(Class<T> clazz) {
                     throw new EventDeserializationException("The content of this event is not a list, consider using 'as' instead");
                 }
                 // should not occur, except if the event is really malformed
-                throw new IllegalStateException("Event content is null");
+                throw new IllegalStateException("Event content is null: the event may be malformed (missing fields)");
             }
             return contentList.stream().map(s -> {
                 try {

powertools-serialization/src/test/java/software/amazon/lambda/powertools/utilities/EventDeserializerTest.java

@@ -129,7 +129,7 @@ public void testDeserializeSQSEventBodyAsWrongObjectType_shouldThrowException(SQ
     public void testDeserializeAPIGatewayNoBody_shouldThrowException(APIGatewayProxyRequestEvent event) {
         assertThatThrownBy(() -> extractDataFrom(event).as(Product.class))
                 .isInstanceOf(IllegalStateException.class)
-                .hasMessage("Event content is null");
+                .hasMessageContaining("Event content is null");
     }
 
     @ParameterizedTest