Small tweaks to fix Error Prone warnings. (#2227)

* Small tweaks to fix Error Prone warnings.

* Add another suppression.

Author: eamonnmcmanus

gson/src/main/java/com/google/gson/internal/bind/JsonTreeReader.java

@@ -277,7 +277,7 @@ JsonElement nextJsonElement() throws IOException {
     JsonToken peeked = peek();
     switch (peeked) {
       case NAME:
-        nextName(true);
+        String unused = nextName(true);
         break;
       case END_ARRAY:
         endArray();

gson/src/test/java/com/google/gson/JsonArrayAsListTest.java

@@ -210,7 +210,7 @@ public void testContains() {
     assertFalse(list.contains(new JsonPrimitive(2)));
     assertFalse(list.contains(null));
 
-    @SuppressWarnings("unlikely-arg-type")
+    @SuppressWarnings({"unlikely-arg-type", "CollectionIncompatibleType"})
     boolean containsInt = list.contains(1); // should only contain JsonPrimitive(1)
     assertFalse(containsInt);
   }
@@ -227,7 +227,7 @@ public void testIndexOf() {
     assertEquals(-1, list.indexOf(new JsonPrimitive(2)));
     assertEquals(-1, list.indexOf(null));
 
-    @SuppressWarnings("unlikely-arg-type")
+    @SuppressWarnings({"unlikely-arg-type", "CollectionIncompatibleType"})
     int indexOfInt = list.indexOf(1); // should only contain JsonPrimitive(1)
     assertEquals(-1, indexOfInt);
 

gson/src/test/java/com/google/gson/JsonObjectAsMapTest.java

@@ -59,7 +59,7 @@ public void testContainsValue() {
     assertFalse(map.containsValue(new JsonPrimitive(2)));
     assertFalse(map.containsValue(null));
 
-    @SuppressWarnings("unlikely-arg-type")
+    @SuppressWarnings({"unlikely-arg-type", "CollectionIncompatibleType"})
     boolean containsInt = map.containsValue(1); // should only contain JsonPrimitive(1)
     assertFalse(containsInt);
   }