Fix #326 (#376)

Signed-off-by: Francesco Guardiani <francescoguard@gmail.com>

Author: slinkydeveloper

core/src/main/java/io/cloudevents/core/v03/CloudEventV03.java

@@ -236,12 +236,12 @@ public String toString() {
             "id='" + id + '\'' +
             ", source=" + source +
             ", type='" + type + '\'' +
-            ", datacontenttype='" + datacontenttype + '\'' +
-            ", schemaurl=" + schemaurl +
-            ", subject='" + subject + '\'' +
-            ", time=" + time +
-            ", data=" + getData() +
-            ", extensions" + this.extensions +
+            ((datacontenttype != null) ? ", datacontenttype='" + datacontenttype + '\'' : "") +
+            ((schemaurl != null) ? ", schemaurl=" + schemaurl : "") +
+            ((subject != null) ? ", subject='" + subject + '\'' : "") +
+            ((time != null) ? ", time=" + time : "") +
+            ((getData() != null) ? ", data=" + getData() : "") +
+            ", extensions=" + this.extensions +
             '}';
     }
 }

core/src/main/java/io/cloudevents/core/v1/CloudEventV1.java

@@ -223,11 +223,11 @@ public String toString() {
             "id='" + id + '\'' +
             ", source=" + source +
             ", type='" + type + '\'' +
-            ", datacontenttype='" + datacontenttype + '\'' +
-            ", dataschema=" + dataschema +
-            ", subject='" + subject + '\'' +
-            ", time=" + time +
-            ", data=" + getData() +
+            ((datacontenttype != null) ? ", datacontenttype='" + datacontenttype + '\'' : "") +
+            ((dataschema != null) ? ", dataschema=" + dataschema : "") +
+            ((subject != null) ? ", subject='" + subject + '\'' : "") +
+            ((time != null) ? ", time=" + time : "") +
+            ((getData() != null) ? ", data=" + getData() : "") +
             ", extensions=" + this.extensions +
             '}';
     }

core/src/test/java/io/cloudevents/core/impl/CloudEventImplTest.java

@@ -91,4 +91,28 @@ public void testGetAttributeNames() {
             );
     }
 
+    @Test
+    public void testToStringV1() {
+        CloudEvent event = CloudEventBuilder.v1()
+            .withId(ID)
+            .withType(TYPE)
+            .withSource(SOURCE)
+            .build();
+
+        assertThat(event.toString())
+            .doesNotContain("time");
+    }
+
+    @Test
+    public void testToStringV03() {
+        CloudEvent event = CloudEventBuilder.v03()
+            .withId(ID)
+            .withType(TYPE)
+            .withSource(SOURCE)
+            .build();
+
+        assertThat(event.toString())
+            .doesNotContain("time");
+    }
+
 }