Stabilize JSON serialization of potentially flakey tests

Closes dropwizard#3284

dropwizard-jackson/src/test/java/io/dropwizard/jackson/Issue1627.java

@@ -1,10 +1,12 @@
 package io.dropwizard.jackson;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 
 import javax.annotation.Nullable;
 import java.util.UUID;
 
+@JsonPropertyOrder(alphabetic = true) // For deterministic serialization
 public class Issue1627 {
 
     @Nullable

dropwizard-jersey/src/test/java/io/dropwizard/jersey/jackson/JacksonMessageBodyProviderTest.java

@@ -291,12 +291,8 @@ private void testValidatedCollectionType(Class<?> klass, Type type) throws IOExc
             new MultivaluedHashMap<>(),
             entity);
 
-        assertThat(obj)
-                .isInstanceOf(klass);
-
-        Iterator<Example> iterator = ((Iterable<Example>) obj).iterator();
-        assertThat(iterator.next().id).isEqualTo(1);
-        assertThat(iterator.next().id).isEqualTo(2);
+        assertThat(obj).isInstanceOf(klass);
+        assertThat((Iterable<Example>) obj).extracting(item -> item.id).contains(1 , 2);
     }
 
 }

dropwizard-json-logging/src/test/java/io/dropwizard/logging/json/layout/JsonFormatterTest.java

@@ -8,15 +8,16 @@
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.Map;
+import java.util.SortedMap;
+import java.util.TreeMap;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class JsonFormatterTest {
 
-    private final Map<String, Object> map = Maps.of(
+    private final SortedMap<String, Object> map = new TreeMap<>(Maps.of(
             "name", "Jim",
-            "hobbies", Arrays.asList("Reading", "Biking", "Snorkeling"));
+            "hobbies", Arrays.asList("Reading", "Biking", "Snorkeling")));
     private final ObjectMapper objectMapper = Jackson.newObjectMapper();
 
     @Test