ADD command failing while building dockerfile using docker-build-step plugin in jenkins
<p>The following is my DockerFile</p>

<pre><code>FROM centos:centos6
MAINTAINER Priyanka

################## Helpful utils
RUN yum -y install sudo
RUN yum -y install curl
RUN yum -y install unzip

################## JDK7

#Note that ADD uncompresses this tarball automatically
ADD jdk-7u79-linux-x64.tar.gz /opt
WORKDIR /opt/jdk1.7.0_79
RUN alternatives --install /usr/bin/java java /opt/jdk1.7.0_79/bin/java 1
RUN alternatives --install /usr/bin/jar jar /opt/jdk1.7.0_79/bin/jar 1
RUN alternatives --install /usr/bin/javac javac /opt/jdk1.7.0_79/bin/javac 1
RUN echo "JAVA_HOME=/opt/jdk1.7.0_79" &gt;&gt; /etc/environment
ENV JAVA_OPTS -Xms1024m -Xmx4196m -XX:NewSize=256m -XX:MaxNewSize=356m -XX:PermSize=256m -XX:MaxPermSize=356m

################## TOMCAT

#Note that ADD uncompresses this tarball automatically
ADD apache-tomcat-7.0.67.tar.gz /usr/share
WORKDIR /usr/share/
RUN mv  apache-tomcat-7.0.67 tomcat7
RUN echo "JAVA_HOME=/opt/jdk1.7.0_79/" &gt;&gt; /etc/default/tomcat7
RUN groupadd tomcat
RUN useradd -s /bin/bash -g tomcat tomcat
RUN chown -Rf tomcat.tomcat /usr/share/tomcat7
EXPOSE 8087

################## ROC Client War Download

RUN curl -O http://10.113.57.164:8080/job/ROC4.0_Client/ws/spark-web/entrypoint/target/entrypoint.war
RUN unzip entrypoint.war -d /usr/share/tomcat7/webapps/roc_client
ADD validation-api-1.1.0.Final.jar /usr/share/tomcat7/webapps/roc_client/WEB-INF/lib/
ADD validation-api-1.1.0.Final-sources.jar /usr/share/tomcat7/webapps/roc_client/WEB-INF/lib/
RUN rm /usr/share/tomcat7/webapps/roc_client/WEB-INF/lib/validation-api-1.0.0.GA-sources.jar 
RUN rm /usr/share/tomcat7/webapps/roc_client/WEB-INF/lib/validation-api-1.0.0.GA.jar

################## Tomcat launch

CMD ["/usr/share/tomcat7/bin/catalina.sh","run"]
</code></pre>

<p>On building this file using docker-build-step in Jenkins the build fails with the following exception at ADD</p>

<pre><code>Step 0 : FROM centos:centos6

 ---&gt; 3bbbf0aca359

Step 1 : MAINTAINER Priyanka

 ---&gt; Using cache

 ---&gt; c8055ba8439a

Step 2 : RUN yum -y install sudo

 ---&gt; Using cache

 ---&gt; 203da82ad2af

Step 3 : RUN yum -y install curl

 ---&gt; Using cache

 ---&gt; c6cb08257236

Step 4 : RUN yum -y install unzip

 ---&gt; Using cache

 ---&gt; 688620db641a

Step 5 : ADD jdk-7u79-linux-x64.tar.gz /opt

ERROR: Build step failed with exception
java.lang.RuntimeException: java.lang.ClassCastException: org.glassfish.json.JsonObjectBuilderImpl$JsonObjectImpl cannot be cast to javax.json.JsonString
    at org.jenkinsci.plugins.dockerbuildstep.cmd.CreateImageCommand.execute(CreateImageCommand.java:139)
    at org.jenkinsci.plugins.dockerbuildstep.DockerBuilder.perform(DockerBuilder.java:75)
    at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
    at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:782)
    at hudson.model.Build$BuildExecution.build(Build.java:205)
    at hudson.model.Build$BuildExecution.doRun(Build.java:162)
    at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:534)
    at hudson.model.Run.execute(Run.java:1738)
    at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
    at hudson.model.ResourceController.execute(ResourceController.java:98)
    at hudson.model.Executor.run(Executor.java:410)
Caused by: java.lang.ClassCastException: org.glassfish.json.JsonObjectBuilderImpl$JsonObjectImpl cannot be cast to javax.json.JsonString
    at org.glassfish.json.JsonObjectBuilderImpl$JsonObjectImpl.getJsonString(JsonObjectBuilderImpl.java:194)
    at org.glassfish.json.JsonObjectBuilderImpl$JsonObjectImpl.getString(JsonObjectBuilderImpl.java:199)
    at org.jenkinsci.plugins.dockerbuildstep.cmd.CreateImageCommand$1.callback(CreateImageCommand.java:123)
    at org.jenkinsci.plugins.dockerbuildstep.cmd.CreateImageCommand.readJsonStream(CreateImageCommand.java:161)
    at org.jenkinsci.plugins.dockerbuildstep.cmd.CreateImageCommand.execute(CreateImageCommand.java:115)
    ... 10 more
Build step 'Execute Docker command' marked build as failure
Finished: FAILURE
</code></pre>

<p>I have run this build many times and it ran successfully without any problem.I made some temporary changes to build configuration and reverted back. Since then it is throwing this  error.
Tried removing off all the docker commands from the File and retained just one RUN command.Still the same issue.It is not able to run any docker commands.</p>