From d1b313a14995b87011c36f6b0ae52091302c3246 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Richard=20K=C3=B6rber?= <github@shredzone.org>
Date: Sun, 16 Apr 2017 16:26:41 +0200
Subject: [PATCH] Return empty JSON array for easier processing

---
 .../java/org/shredzone/acme4j/Authorization.java   |  2 +-
 .../main/java/org/shredzone/acme4j/Metadata.java   | 11 +++--------
 .../acme4j/connector/ResourceIterator.java         |  9 +++------
 .../main/java/org/shredzone/acme4j/util/JSON.java  | 11 +++++++++--
 .../java/org/shredzone/acme4j/util/JSONTest.java   | 14 ++++++++++++++
 5 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/Authorization.java b/acme4j-client/src/main/java/org/shredzone/acme4j/Authorization.java
index 77472a9b..28634ac3 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/Authorization.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/Authorization.java
@@ -272,7 +272,7 @@ public class Authorization extends AcmeResource {
      */
     private List<List<Challenge>> fetchCombinations(JSON json, List<Challenge> challenges) {
         JSON.Array jsonCombinations = json.get("combinations").asArray();
-        if (jsonCombinations == null) {
+        if (jsonCombinations.isEmpty()) {
             return Arrays.asList(challenges);
         }
 
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/Metadata.java b/acme4j-client/src/main/java/org/shredzone/acme4j/Metadata.java
index 6448fb86..f3d25105 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/Metadata.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/Metadata.java
@@ -17,10 +17,8 @@ import static java.util.stream.Collectors.toList;
 
 import java.net.URI;
 import java.util.Collection;
-import java.util.Collections;
 
 import org.shredzone.acme4j.util.JSON;
-import org.shredzone.acme4j.util.JSON.Array;
 import org.shredzone.acme4j.util.JSON.Value;
 
 /**
@@ -61,12 +59,9 @@ public class Metadata {
      * itself for the purposes of CAA record validation. Empty if not available.
      */
     public Collection<String> getCaaIdentities() {
-        Array array = meta.get("caa-identities").asArray();
-        if (array == null) {
-            return Collections.emptyList();
-        }
-
-        return array.stream().map(Value::asString).collect(toList());
+        return meta.get("caa-identities").asArray().stream()
+                .map(Value::asString)
+                .collect(toList());
     }
 
     /**
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/ResourceIterator.java b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/ResourceIterator.java
index 0ef74d32..5bf80717 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/ResourceIterator.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/ResourceIterator.java
@@ -157,12 +157,9 @@ public class ResourceIterator<T extends AcmeResource> implements Iterator<T> {
      *            JSON map to read from
      */
     private void fillUriList(JSON json) {
-        JSON.Array array = json.get(field).asArray();
-        if (array == null) {
-            return;
-        }
-
-        array.stream().map(JSON.Value::asURI).forEach(uriList::add);
+        json.get(field).asArray().stream()
+                .map(JSON.Value::asURI)
+                .forEach(uriList::add);
     }
 
 }
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/util/JSON.java b/acme4j-client/src/main/java/org/shredzone/acme4j/util/JSON.java
index a17be6ee..87d61620 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/util/JSON.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/util/JSON.java
@@ -207,6 +207,13 @@ public final class JSON implements Serializable {
             return data.size();
         }
 
+        /**
+         * Returns {@code true} if the array is empty.
+         */
+        public boolean isEmpty() {
+            return data.isEmpty();
+        }
+
         /**
          * Gets the {@link Value} at the given index.
          *
@@ -298,11 +305,11 @@ public final class JSON implements Serializable {
         /**
          * Returns the value as JSON array.
          *
-         * @return {@link JSON.Array}, or {@code null} if the value was not set.
+         * @return {@link JSON.Array}, which is empty if the value was not set.
          */
         public Array asArray() {
             if (val == null) {
-                return null;
+                return new Array(path, Collections.emptyList());
             }
 
             try {
diff --git a/acme4j-client/src/test/java/org/shredzone/acme4j/util/JSONTest.java b/acme4j-client/src/test/java/org/shredzone/acme4j/util/JSONTest.java
index 110f8e4b..b30f0d46 100644
--- a/acme4j-client/src/test/java/org/shredzone/acme4j/util/JSONTest.java
+++ b/acme4j-client/src/test/java/org/shredzone/acme4j/util/JSONTest.java
@@ -102,12 +102,26 @@ public class JSONTest {
         JSON.Array array = json.get("array").asArray();
 
         assertThat(array.size(), is(4));
+        assertThat(array.isEmpty(), is(false));
         assertThat(array.get(0), is(notNullValue()));
         assertThat(array.get(1), is(notNullValue()));
         assertThat(array.get(2), is(notNullValue()));
         assertThat(array.get(3), is(notNullValue()));
     }
 
+    /**
+     * Test empty array.
+     */
+    @Test
+    public void testEmptyArray() {
+        JSON json = TestUtils.getJsonAsObject("json");
+        JSON.Array array = json.get("missingArray").asArray();
+
+        assertThat(array.size(), is(0));
+        assertThat(array.isEmpty(), is(true));
+        assertThat(array.stream().count(), is(0L));
+    }
+
     /**
      * Test all array iterator related methods.
      */