Fix mail dependency issue. (#405)

Author: tobiasake

pom.xml

@@ -385,6 +385,12 @@
             <groupId>com.github.java-json-tools</groupId>
             <artifactId>json-schema-validator</artifactId>
             <version>2.2.8</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>javax.mail</groupId>
+                    <artifactId>mailapi</artifactId>
+                </exclusion>
+            </exclusions>
         </dependency>
     </dependencies>