slf4j - Why is a Maven plugin failing with error messages about 'API incompatibility', 'foreign imports' and the 'maven.api Class realm'? -

i have spent better part of afternoon trying solve maven problem jetty plugin telling me wouldn't run because slf4j dependencies had incompatible api messageformatter.arrayformat(ljava/lang/string;[ljava/lang/object;)lorg/slf4j/helpers/formattingtuple

[info] --- jetty-maven-plugin:9.0.4.v20130625:run (start-jetty-before-integration-tests) @ scala-spring-hibernate-maven-webapp --- [info] ------------------------------------------------------------------------ [info] build failure [info] ------------------------------------------------------------------------ [info] total time: 27.167s [info] finished at: wed jul 31 16:23:57 est 2013 [info] final memory: 12m/30m [info] ------------------------------------------------------------------------ [error] failed execute goal org.eclipse.jetty:jetty-maven-plugin:9.0.4.v20130625:run (start-jetty-before-integration-tests) on project scala-spring-hibernate-maven-webapp: execution start-jetty-before-integration-tests of goal org.eclipse.jetty:jetty-maven-plugin:9.0.4.v20130625:run failed: unable load mojo 'run' in plugin 'org.eclipse.jetty:jetty-maven-plugin:9.0.4.v20130625' due api incompatibility: org.codehaus.plexus.component.repository.exception.componentlookupexception: org.slf4j.helpers.messageformatter.arrayformat(ljava/lang/string;[ljava/lang/object;)lorg/slf4j/helpers/formattingtuple; [error] ----------------------------------------------------- [error] realm =    plugin>org.eclipse.jetty:jetty-maven-plugin:9.0.4.v20130625 [error] strategy = org.codehaus.plexus.classworlds.strategy.selffirststrategy [error] urls[0] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-maven-plugin/9.0.4.v20130625/jetty-maven-plugin-9.0.4.v20130625.jar [error] urls[1] = file:/users/graham/.m2/repository/org/sonatype/sisu/sisu-inject-bean/2.1.1/sisu-inject-bean-2.1.1.jar [error] urls[2] = file:/users/graham/.m2/repository/org/sonatype/sisu/sisu-guice/2.9.4/sisu-guice-2.9.4-no_aop.jar [error] urls[3] = file:/users/graham/.m2/repository/org/codehaus/plexus/plexus-utils/2.0.6/plexus-utils-2.0.6.jar [error] urls[4] = file:/users/graham/.m2/repository/org/sonatype/aether/aether-util/1.11/aether-util-1.11.jar [error] urls[5] = file:/users/graham/.m2/repository/org/codehaus/plexus/plexus-interpolation/1.14/plexus-interpolation-1.14.jar [error] urls[6] = file:/users/graham/.m2/repository/org/codehaus/plexus/plexus-component-annotations/1.5.5/plexus-component-annotations-1.5.5.jar [error] urls[7] = file:/users/graham/.m2/repository/org/sonatype/plexus/plexus-sec-dispatcher/1.3/plexus-sec-dispatcher-1.3.jar [error] urls[8] = file:/users/graham/.m2/repository/org/sonatype/plexus/plexus-cipher/1.4/plexus-cipher-1.4.jar [error] urls[9] = file:/users/graham/.m2/repository/org/apache/maven/plugin-tools/maven-plugin-tools-api/3.1/maven-plugin-tools-api-3.1.jar [error] urls[10] = file:/users/graham/.m2/repository/backport-util-concurrent/backport-util-concurrent/3.1/backport-util-concurrent-3.1.jar [error] urls[11] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-util/9.0.4.v20130625/jetty-util-9.0.4.v20130625.jar [error] urls[12] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-webapp/9.0.4.v20130625/jetty-webapp-9.0.4.v20130625.jar [error] urls[13] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-xml/9.0.4.v20130625/jetty-xml-9.0.4.v20130625.jar [error] urls[14] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-servlet/9.0.4.v20130625/jetty-servlet-9.0.4.v20130625.jar [error] urls[15] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-jaas/9.0.4.v20130625/jetty-jaas-9.0.4.v20130625.jar [error] urls[16] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-security/9.0.4.v20130625/jetty-security-9.0.4.v20130625.jar [error] urls[17] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-plus/9.0.4.v20130625/jetty-plus-9.0.4.v20130625.jar [error] urls[18] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/javax.transaction/1.1.1.v201105210645/javax.transaction-1.1.1.v201105210645.jar [error] urls[19] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-jndi/9.0.4.v20130625/jetty-jndi-9.0.4.v20130625.jar [error] urls[20] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/javax.mail.glassfish/1.4.1.v201005082020/javax.mail.glassfish-1.4.1.v201005082020.jar [error] urls[21] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/javax.activation/1.1.0.v201105071233/javax.activation-1.1.0.v201105071233.jar [error] urls[22] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-server/9.0.4.v20130625/jetty-server-9.0.4.v20130625.jar [error] urls[23] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/javax.servlet/3.0.0.v201112011016/javax.servlet-3.0.0.v201112011016.jar [error] urls[24] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-http/9.0.4.v20130625/jetty-http-9.0.4.v20130625.jar [error] urls[25] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-io/9.0.4.v20130625/jetty-io-9.0.4.v20130625.jar [error] urls[26] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-jmx/9.0.4.v20130625/jetty-jmx-9.0.4.v20130625.jar [error] urls[27] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-annotations/9.0.4.v20130625/jetty-annotations-9.0.4.v20130625.jar [error] urls[28] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/javax.annotation/1.1.0.v201108011116/javax.annotation-1.1.0.v201108011116.jar [error] urls[29] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/org.objectweb.asm/3.1.0.v200803061910/org.objectweb.asm-3.1.0.v200803061910.jar [error] urls[30] = file:/users/graham/.m2/repository/org/eclipse/jetty/websocket/websocket-server/9.0.4.v20130625/websocket-server-9.0.4.v20130625.jar [error] urls[31] = file:/users/graham/.m2/repository/org/eclipse/jetty/websocket/websocket-common/9.0.4.v20130625/websocket-common-9.0.4.v20130625.jar [error] urls[32] = file:/users/graham/.m2/repository/org/eclipse/jetty/websocket/websocket-api/9.0.4.v20130625/websocket-api-9.0.4.v20130625.jar [error] urls[33] = file:/users/graham/.m2/repository/org/eclipse/jetty/websocket/websocket-client/9.0.4.v20130625/websocket-client-9.0.4.v20130625.jar [error] urls[34] = file:/users/graham/.m2/repository/org/eclipse/jetty/websocket/websocket-servlet/9.0.4.v20130625/websocket-servlet-9.0.4.v20130625.jar [error] urls[35] = file:/users/graham/.m2/repository/org/eclipse/jetty/jetty-jsp/9.0.4.v20130625/jetty-jsp-9.0.4.v20130625.jar [error] urls[36] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/javax.servlet.jsp/2.2.0.v201112011158/javax.servlet.jsp-2.2.0.v201112011158.jar [error] urls[37] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/org.apache.jasper.glassfish/2.2.2.v201112011158/org.apache.jasper.glassfish-2.2.2.v201112011158.jar [error] urls[38] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/javax.servlet.jsp.jstl/1.2.0.v201105211821/javax.servlet.jsp.jstl-1.2.0.v201105211821.jar [error] urls[39] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/org.apache.taglibs.standard.glassfish/1.2.0.v201112081803/org.apache.taglibs.standard.glassfish-1.2.0.v201112081803.jar [error] urls[40] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/javax.el/2.2.0.v201303151357/javax.el-2.2.0.v201303151357.jar [error] urls[41] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/com.sun.el/2.2.0.v201303151357/com.sun.el-2.2.0.v201303151357.jar [error] urls[42] = file:/users/graham/.m2/repository/org/eclipse/jetty/orbit/org.eclipse.jdt.core/3.8.2.v20130121/org.eclipse.jdt.core-3.8.2.v20130121.jar [error] number of foreign imports: 1 [error] import: entry[import  realm classrealm[maven.api, parent: null]] [error] [error] ----------------------------------------------------- [error] -> [help 1] [error] [error] see full stack trace of errors, re-run maven -e switch. [error] re-run maven using -x switch enable full debug logging. [error] [error] more information errors , possible solutions, please read following articles: [error] [help 1] http://cwiki.apache.org/confluence/display/maven/plugincontainerexception 

it occurred me in lib/ext directory of jdk (on mac, equivalent directories /library/java/extensions , $home/library/java/extensions) and, lo , behold, there version of slf4j in there, along bunch of other stuff. removing slf4j jars got build working again.

(note: have had ato's auskey software deposit things in lib/ext directory before, why thought there. haven't yet checked see whether auskey still work after removed slf4j directory.)