While containerizing web app , it gets stuck at copying war file

Question

[INFO] --- docker-maven-plugin:1.0.0:build (default) @ bookstore ---
18:35:34.921 [main] DEBUG com.spotify.docker.client.DockerCertificates - /root/.docker/ca.pem, /root/.docker/key.pem or /root/.docker/cert.pem does not exist, not using SSL
18:35:35.076 [main] DEBUG com.spotify.docker.client.DockerConfigReader - Using configfile: /root/.dockercfg 
[WARNING] No entry found in settings.xml for serverId=docker-hub, cannot configure authentication for that registry
[INFO] Using authentication suppliers: [ConfigFileRegistryAuthSupplier]
[INFO] Copying /home/ales/Git/BookStore/target/bookstore-1.war -> /home/ales/Git/BookStore/target/docker/bookstore-1.war

i am trying to containerizing the java web app (which i have got from web as a sample) , i am using maven to build app and using spotify plugin to convert war to dockerimage.

when i run mvn clean package docker:build it gets stuck copying step and doesn't proceed further.

Note: my project name is Bookstore.

This is the error that issued after a long run of copy command ,

[INFO] 
[INFO] --- maven-war-plugin:2.6:war (default-war) @ bookstore ---
[INFO] Packaging webapp
[INFO] Assembling webapp [bookstore] in [/home/ales/Git/BookStore/target/bookstore-1]
[INFO] Processing war project
[INFO] Copying webapp resources [/home/ales/Git/BookStore/WebContent]
[INFO] Webapp assembled in [110 msecs]
[INFO] Building war: /home/ales/Git/BookStore/target/bookstore-1.war
[INFO] 
[INFO] --- docker-maven-plugin:1.0.0:build (default) @ bookstore ---
23:31:08.311 [main] DEBUG com.spotify.docker.client.DockerCertificates - /home/ales/.docker/ca.pem, /home/ales/.docker/key.pem or /home/ales/.docker/cert.pem does not exist, not using SSL
23:31:08.567 [main] DEBUG com.spotify.docker.client.DockerConfigReader - Using configfile: /home/ales/.docker/config.json
[WARNING] No entry found in settings.xml for serverId=docker-hub, cannot configure authentication for that registry
[INFO] Using authentication suppliers: [ConfigFileRegistryAuthSupplier]
[INFO] Copying /home/ales/Git/BookStore/target/bookstore-1.war -> /home/ales/Git/BookStore/target/docker/bookstore-1.war
[ERROR] Java heap space -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/OutOfMemoryError