Update GuavaImmutableMapDeserializer.java

Author: josethomas

src/main/java/com/fasterxml/jackson/datatype/guava/deser/GuavaImmutableMapDeserializer.java

@@ -45,7 +45,9 @@ protected T _deserializeEntries(JsonParser jp, DeserializationContext ctxt) thro
             } else {
                 value = valueDes.deserializeWithType(jp, ctxt, typeDeser);
             }
-            builder.put(key, value);
+            if (null != value) {
+                builder.put(key, value);
+            }
         }
         // No class outside of the package will be able to subclass us,
         // and we provide the proper builder for the subclasses we implement.
@@ -54,4 +56,4 @@ protected T _deserializeEntries(JsonParser jp, DeserializationContext ctxt) thro
         return map;
     }
 
-}
+}