From 6484e5ecaf0bae2ebd66f1a1790c36c0d63fd41e Mon Sep 17 00:00:00 2001
From: Jens Schauder <jschauder@pivotal.io>
Date: Mon, 14 Jan 2019 15:12:56 +0100
Subject: [PATCH] #784 - Polishing.

Tested and fixed NPE with empty pojo.
---
 .../hateoas/uber/Jackson2UberModule.java      | 15 +++++---
 .../uber/Jackson2UberIntegrationTest.java     | 23 +++++++++++-
 ...with-resource-objects-and-empty-value.json | 36 +++++++++++++++++++
 3 files changed, 69 insertions(+), 5 deletions(-)
 create mode 100644 src/test/resources/org/springframework/hateoas/uber/resources-with-resource-objects-and-empty-value.json

diff --git a/src/main/java/org/springframework/hateoas/uber/Jackson2UberModule.java b/src/main/java/org/springframework/hateoas/uber/Jackson2UberModule.java
index 4a4af6d7c..704976b69 100644
--- a/src/main/java/org/springframework/hateoas/uber/Jackson2UberModule.java
+++ b/src/main/java/org/springframework/hateoas/uber/Jackson2UberModule.java
@@ -640,14 +640,21 @@ private static Resources<?> extractResources(UberDocument doc, JavaType rootType
 					} else {
 
 						// Primitive type
-						if (item.getData().size() == 1 && item.getData().get(0).getName() == null) {
+						List<UberData> itemData = item.getData();
+						if (itemData != null && itemData.size() == 1 && itemData.get(0).getName() == null) {
 
-							Object scalarValue = item.getData().get(0).getValue();
+							Object scalarValue = itemData.get(0).getValue();
 							resource = new Resource<>(scalarValue, uberData.getLinks());
 						} else {
 
-							Map<String, Object> properties = item.getData().stream()
-									.collect(Collectors.toMap(UberData::getName, UberData::getValue));
+							Map<String, Object> properties;
+							if (itemData == null) {
+								properties = new HashMap<>();
+							} else {
+								properties = itemData.stream() //
+										.collect(Collectors.toMap(UberData::getName, UberData::getValue));
+							}
+
 							Object obj = PropertyUtils.createObjectFromProperties(rootType.getRawClass(), properties);
 							resource = new Resource<>(obj, uberData.getLinks());
 						}
diff --git a/src/test/java/org/springframework/hateoas/uber/Jackson2UberIntegrationTest.java b/src/test/java/org/springframework/hateoas/uber/Jackson2UberIntegrationTest.java
index c4e0842ec..9034c5571 100644
--- a/src/test/java/org/springframework/hateoas/uber/Jackson2UberIntegrationTest.java
+++ b/src/test/java/org/springframework/hateoas/uber/Jackson2UberIntegrationTest.java
@@ -299,6 +299,28 @@ public void deserializeResources() throws Exception {
 		assertThat(actual).isEqualTo(expected);
 	}
 
+	/**
+	 * @see #784
+	 */
+	@Test
+	public void deserializeEmptyValue() throws Exception {
+
+		List<Resource<String>> data = new ArrayList<Resource<String>>();
+		data.add(new Resource<>("", new Link("localhost"), new Link("orders").withRel("orders")));
+		data.add(new Resource<>("second", new Link("remotehost"), new Link("order").withRel("orders")));
+
+		Resources expected = new Resources<>(data);
+		expected.add(new Link("localhost"));
+		expected.add(new Link("/page/2").withRel("next"));
+
+		Resources<Resource<String>> actual = mapper.readValue(
+				MappingUtils.read(new ClassPathResource("resources-with-resource-objects-and-empty-value.json", getClass())),
+				mapper.getTypeFactory().constructParametricType(Resources.class,
+						mapper.getTypeFactory().constructParametricType(Resource.class, String.class)));
+
+		assertThat(actual).isEqualTo(expected);
+	}
+
 	/**
 	 * @see #784
 	 */
@@ -321,7 +343,6 @@ public void deserializeEmptyResources() throws Exception {
 								mapper.getTypeFactory().constructParametricType(Resource.class, String.class) //
 						) //
 		)).isInstanceOf(RuntimeException.class);
-
 	}
 
 	/**
diff --git a/src/test/resources/org/springframework/hateoas/uber/resources-with-resource-objects-and-empty-value.json b/src/test/resources/org/springframework/hateoas/uber/resources-with-resource-objects-and-empty-value.json
new file mode 100644
index 000000000..e1dd7a393
--- /dev/null
+++ b/src/test/resources/org/springframework/hateoas/uber/resources-with-resource-objects-and-empty-value.json
@@ -0,0 +1,36 @@
+{
+  "uber" : {
+    "version" : "1.0",
+    "data" : [ {
+      "rel" : [ "self" ],
+      "url" : "localhost"
+    }, {
+      "rel" : [ "next" ],
+      "url" : "/page/2"
+    }, {
+      "data" : [ {
+        "rel" : [ "self" ],
+        "url" : "localhost"
+      }, {
+        "rel" : [ "orders" ],
+        "url" : "orders"
+      }, {
+        "name" : "string",
+        "data" : []
+      } ]
+    }, {
+      "data" : [ {
+        "rel" : [ "self" ],
+        "url" : "remotehost"
+      }, {
+        "rel" : [ "orders" ],
+        "url" : "order"
+      }, {
+        "name" : "string",
+        "data" : [ {
+          "value" : "second"
+        } ]
+      } ]
+    } ]
+  }
+}
\ No newline at end of file