NullPointerException for import

module ospf {
namespace "urn:cisco:params:xml:ns:yang:ospf";
prefix ospf;
import ietf-inet-types

revision 2020-10-20;
}

Log:

1st run:
build success

2nd run:
[DEBUG] Configuring mojo 'org.onosproject:yangutils-maven-plugin:1.0.0-SNAPSHOT:yang2java' with basic configurator -->
[DEBUG] (f) baseDir = /home/root1/onos/utils/test
[DEBUG] (f) genFilesDir = src/main/java
[DEBUG] (f) outputDirectory = /home/root1/onos/utils/test/target/classes
[DEBUG] (f) project = MavenProject: org.onosproject:onlab-test:1.6.0-SNAPSHOT @ /home/root1/onos/utils/test/pom.xml
[DEBUG] (f) yangFilesDir = src/main/yang
[DEBUG] – end configuration –
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.457 s
[INFO] Finished at: 2016-05-18T12:39:37+05:30
[INFO] Final Memory: 19M/313M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.onosproject:yangutils-maven-plugin:1.0.0-SNAPSHOT:yang2java (default) on project onlab-test: Execution default of goal org.onosproject:yangutils-maven-plugin:1.0.0-SNAPSHOT:yang2java failed. NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.onosproject:yangutils-maven-plugin:1.0.0-SNAPSHOT:yang2java (default) on project onlab-test: Execution default of goal org.onosproject:yangutils-maven-plugin:1.0.0-SNAPSHOT:yang2java failed.
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:224)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:862)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:286)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default of goal org.onosproject:yangutils-maven-plugin:1.0.0-SNAPSHOT:yang2java failed.
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
... 20 more
Caused by: java.lang.NullPointerException
at org.onosproject.yangutils.translator.tojava.JavaCodeGeneratorUtil.freeRestResources(JavaCodeGeneratorUtil.java:168)
at org.onosproject.yangutils.translator.tojava.JavaCodeGeneratorUtil.translatorErrorHandler(JavaCodeGeneratorUtil.java:219)
at org.onosproject.yangutils.plugin.manager.YangUtilManager.execute(YangUtilManager.java:182)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
... 21 more
[ERROR]
[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/PluginExecutionException
root1@root1-HP-EliteBook-840-G2:~/onos/utils/test$