Fixes for reviews. Hope i did not forget something.

extensions/gson/src/main/java/io/jsonwebtoken/gson/io/GsonDeserializer.java

@@ -1,6 +1,8 @@
-package io.jsonwebtoken.io;
+package io.jsonwebtoken.gson.io;
 
 import com.google.gson.Gson;
+import io.jsonwebtoken.io.DeserializationException;
+import io.jsonwebtoken.io.Deserializer;
 import io.jsonwebtoken.lang.Assert;
 import java.io.IOException;
 

extensions/gson/src/main/java/io/jsonwebtoken/gson/io/GsonSerializer.java

@@ -1,7 +1,10 @@
-package io.jsonwebtoken.io;
+package io.jsonwebtoken.gson.io;
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
+import io.jsonwebtoken.io.Encoders;
+import io.jsonwebtoken.io.SerializationException;
+import io.jsonwebtoken.io.Serializer;
 import io.jsonwebtoken.lang.Assert;
 import io.jsonwebtoken.lang.Strings;
 
@@ -24,8 +27,12 @@ public class GsonSerializer<T> implements Serializer<T> {
     @Override
     public byte[] serialize(T t) throws SerializationException {
         Assert.notNull(t, "Object to serialize cannot be null.");
-        //Gson never throws any serialization exception 
-        return writeValueAsBytes(t);
+        try {
+            return writeValueAsBytes(t);
+        } catch (Exception e) {
+            String msg = "Unable to serialize object: " + e.getMessage();
+            throw new SerializationException(msg, e);
+        }
     }
 
     @SuppressWarnings("WeakerAccess") //for testing

extensions/pom.xml

@@ -36,7 +36,7 @@
     <modules>
         <module>jackson</module>
         <module>orgjson</module>
-	<module>gson</module>
+        <module>gson</module>
     </modules>
 
 </project>

impl/pom.xml

@@ -54,11 +54,11 @@
             <artifactId>jjwt-orgjson</artifactId>
             <scope>test</scope>
         </dependency>
-	<dependency>
+        <dependency>
             <groupId>io.jsonwebtoken</groupId>
             <artifactId>jjwt-gson</artifactId>
-	    <scope>test</scope>
-	</dependency>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
 </project>

impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathDeserializerLocator.java

@@ -34,8 +34,8 @@ public class RuntimeClasspathDeserializerLocator<T> implements InstanceLocator<D
             return Classes.newInstance("io.jsonwebtoken.io.JacksonDeserializer");
         } else if (isAvailable("io.jsonwebtoken.io.OrgJsonDeserializer")) {
             return Classes.newInstance("io.jsonwebtoken.io.OrgJsonDeserializer");
-        } else if (isAvailable("io.jsonwebtoken.io.GsonDeserializer")) {
-            return Classes.newInstance("io.jsonwebtoken.io.GsonDeserializer");
+        } else if (isAvailable("io.jsonwebtoken.gson.io.GsonDeserializer")) {
+            return Classes.newInstance("io.jsonwebtoken.gson.io.GsonDeserializer");
         } else {
             throw new IllegalStateException("Unable to discover any JSON Deserializer implementations on the classpath.");
         }

impl/src/main/java/io/jsonwebtoken/impl/io/RuntimeClasspathSerializerLocator.java

@@ -34,8 +34,8 @@ public class RuntimeClasspathSerializerLocator implements InstanceLocator<Serial
             return Classes.newInstance("io.jsonwebtoken.io.JacksonSerializer");
         } else if (isAvailable("io.jsonwebtoken.io.OrgJsonSerializer")) {
             return Classes.newInstance("io.jsonwebtoken.io.OrgJsonSerializer");
-        } else if (isAvailable("io.jsonwebtoken.io.GsonSerializer")) {
-            return Classes.newInstance("io.jsonwebtoken.io.GsonSerializer");
+        } else if (isAvailable("io.jsonwebtoken.gson.io.GsonSerializer")) {
+            return Classes.newInstance("io.jsonwebtoken.gson.io.GsonSerializer");
         } else {
             throw new IllegalStateException("Unable to discover any JSON Serializer implementations on the classpath.");
         }

pom.xml

@@ -90,7 +90,7 @@
 
         <jackson.version>2.9.9.1</jackson.version>
         <orgjson.version>20180130</orgjson.version>
-	<gson.version>2.8.5</gson.version>
+        <gson.version>2.8.5</gson.version>
 
         <!-- Optional Runtime Dependencies: -->
         <bouncycastle.version>1.60</bouncycastle.version>
@@ -132,7 +132,7 @@
                 <artifactId>jjwt-orgjson</artifactId>
                 <version>${project.version}</version>
             </dependency>
-	    <dependency>
+            <dependency>
                 <groupId>io.jsonwebtoken</groupId>
                 <artifactId>jjwt-gson</artifactId>
                 <version>${project.version}</version>
@@ -147,7 +147,7 @@
                 <artifactId>json</artifactId>
                 <version>${orgjson.version}</version>
             </dependency>
-	    <dependency>
+            <dependency>
                 <groupId>com.google.code.gson</groupId>
                 <artifactId>gson</artifactId>
                 <version>${gson.version}</version>