title: java.lang.LinkageError: loader constraint violation: when resolving method
body: <p>I have the following:</p>
  
  <h1>1. EJB in business tier</h1>
  
  <pre><code>package ejb.x.y;
  
  @Stateless
  public class FileFormatConvertor {  
      public byte[] fromExcelToCsv(Workbook workbook, Sheet sheet, String delimiter) throws Exception {
          ...
  }
  </code></pre>
  
  <h1>2. Bean in the web tier</h1>
  
  <pre><code>package web.x.y;
  
  @Named
  @SessionScoped
  public class FileUploadViewAction implements Serializable {
      @EJB
      private FileFormatConvertor fileFormatConvertor ;   
      // Other declarations
      if (fileType == Type.EXCEL) {
          bytesToUpload =   fileFormatConvertor.fromExcelToCsv(workbook, sheet, delimiter);
      }
      // Rest of code
  }
  </code></pre>
  
  <h1>3. POM Files</h1>
  
  <p>Ear pom.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"&gt;
      &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
      &lt;parent&gt;
          &lt;artifactId&gt;xy-portal&lt;/artifactId&gt;
          &lt;groupId&gt;com.xy&lt;/groupId&gt;
          &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
      &lt;/parent&gt;
      &lt;groupId&gt;com.xy&lt;/groupId&gt;
      &lt;artifactId&gt;ear-x-y&lt;/artifactId&gt;
      &lt;version&gt;${project.version}&lt;/version&gt;
      &lt;packaging&gt;ear&lt;/packaging&gt;
      &lt;name&gt;ear-x-y&lt;/name&gt;
      &lt;properties&gt;
          &lt;project.build.sourceEncoding&gt;UTF-8&lt;/project.build.sourceEncoding&gt;
      &lt;/properties&gt;
      &lt;build&gt;
          &lt;finalName&gt;ear-x-y&lt;/finalName&gt;
          &lt;plugins&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
                  &lt;artifactId&gt;maven-compiler-plugin&lt;/artifactId&gt;
                  &lt;version&gt;2.3.2&lt;/version&gt;
                  &lt;configuration&gt;
                      &lt;source&gt;1.6&lt;/source&gt;
                      &lt;target&gt;1.6&lt;/target&gt;
                  &lt;/configuration&gt;
              &lt;/plugin&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
                  &lt;artifactId&gt;maven-ear-plugin&lt;/artifactId&gt;
                  &lt;version&gt;2.6&lt;/version&gt;
                  &lt;configuration&gt;
                      &lt;version&gt;6&lt;/version&gt;
                      &lt;defaultLibBundleDir&gt;lib&lt;/defaultLibBundleDir&gt;
                      &lt;modules&gt;
                          &lt;webModule&gt;
                              &lt;groupId&gt;com.xy&lt;/groupId&gt;
                              &lt;artifactId&gt;web-x-y&lt;/artifactId&gt;
                              &lt;contextRoot&gt;/xy&lt;/contextRoot&gt;
                              &lt;bundleFileName&gt;xy-portal-web.war&lt;/bundleFileName&gt;
                          &lt;/webModule&gt;
                          &lt;ejbModule&gt;
                              &lt;groupId&gt;com.xy&lt;/groupId&gt;
                              &lt;artifactId&gt;ejb-x-y&lt;/artifactId&gt;
                              &lt;bundleFileName&gt;xy-portal-ejb.jar&lt;/bundleFileName&gt;
                          &lt;/ejbModule&gt;
                      &lt;/modules&gt;
                  &lt;/configuration&gt;
              &lt;/plugin&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.jboss.as.plugins&lt;/groupId&gt;
                  &lt;artifactId&gt;jboss-as-maven-plugin&lt;/artifactId&gt;
                  &lt;configuration&gt;
                      &lt;skip&gt;false&lt;/skip&gt;  
                      &lt;hostname&gt;0.0.0.0&lt;/hostname&gt;
                      &lt;!--&lt;hostname&gt;xy&lt;/hostname&gt;--&gt;
                      &lt;port&gt;0000&lt;/port&gt;
                      &lt;filename&gt;xy-portal-ear.ear&lt;/filename&gt;
                  &lt;/configuration&gt;
              &lt;/plugin&gt;
          &lt;/plugins&gt;
      &lt;/build&gt;
      &lt;dependencies&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.xy&lt;/groupId&gt;
              &lt;artifactId&gt;xy-portal-ejb&lt;/artifactId&gt;
              &lt;version&gt;${project.version}&lt;/version&gt;
              &lt;type&gt;ejb&lt;/type&gt;
          &lt;/dependency&gt;   
          &lt;dependency&gt;
              &lt;groupId&gt;com.xy&lt;/groupId&gt;
              &lt;artifactId&gt;xy-portal-web&lt;/artifactId&gt;
              &lt;version&gt;${project.version}&lt;/version&gt;
              &lt;type&gt;war&lt;/type&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.resteasy&lt;/groupId&gt;
              &lt;artifactId&gt;resteasy-jaxb-provider&lt;/artifactId&gt;
              &lt;version&gt;2.3.1.GA&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.resteasy&lt;/groupId&gt;
              &lt;artifactId&gt;resteasy-jaxrs&lt;/artifactId&gt;
              &lt;version&gt;2.3.1.GA&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;${project.groupId}&lt;/groupId&gt;
              &lt;artifactId&gt;xy-client&lt;/artifactId&gt;
              &lt;version&gt;${project.version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;${project.groupId}&lt;/groupId&gt;
              &lt;artifactId&gt;xy-datamodel&lt;/artifactId&gt;
              &lt;version&gt;${project.version}&lt;/version&gt;
          &lt;/dependency&gt;       
      &lt;/dependencies&gt;    
  &lt;/project&gt;
  </code></pre>
  
  <p>Ejb pom.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"&gt;    
      &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
      &lt;parent&gt;
          &lt;artifactId&gt;xy-portal&lt;/artifactId&gt;
          &lt;groupId&gt;com.xy&lt;/groupId&gt;
          &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
      &lt;/parent&gt;
      &lt;groupId&gt;com.xy&lt;/groupId&gt;
      &lt;artifactId&gt;xy-portal-ejb&lt;/artifactId&gt;
      &lt;version&gt;${project.version}&lt;/version&gt;
      &lt;packaging&gt;ejb&lt;/packaging&gt;
      &lt;name&gt;xy-portal-ejb&lt;/name&gt;
      &lt;properties&gt;
          &lt;endorsed.dir&gt;${project.build.directory}/endorsed&lt;/endorsed.dir&gt;
          &lt;project.build.sourceEncoding&gt;UTF-8&lt;/project.build.sourceEncoding&gt;
      &lt;/properties&gt;
      &lt;dependencies&gt;          
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.as&lt;/groupId&gt;
              &lt;artifactId&gt;jboss-as-ejb3&lt;/artifactId&gt;
              &lt;version&gt;7.1.2.Final&lt;/version&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
              &lt;exclusions&gt;
                  &lt;exclusion&gt;
                      &lt;groupId&gt;org.hibernate&lt;/groupId&gt;
                      &lt;artifactId&gt;hibernate-validator&lt;/artifactId&gt;
                  &lt;/exclusion&gt;
              &lt;/exclusions&gt;
          &lt;/dependency&gt;      
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.spec&lt;/groupId&gt;
              &lt;artifactId&gt;jboss-javaee-6.0&lt;/artifactId&gt;
              &lt;version&gt;3.0.3.Final&lt;/version&gt;
              &lt;type&gt;pom&lt;/type&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.infinispan&lt;/groupId&gt;
              &lt;artifactId&gt;infinispan-core&lt;/artifactId&gt;
              &lt;version&gt;6.0.2.Final&lt;/version&gt;
          &lt;/dependency&gt;        
          &lt;dependency&gt;
              &lt;groupId&gt;org.apache.poi&lt;/groupId&gt;
              &lt;artifactId&gt;poi&lt;/artifactId&gt;
              &lt;version&gt;3.14&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.apache.poi&lt;/groupId&gt;
              &lt;artifactId&gt;poi-ooxml&lt;/artifactId&gt;
              &lt;version&gt;3.14&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.apache.poi&lt;/groupId&gt;
              &lt;artifactId&gt;poi-ooxml-schemas&lt;/artifactId&gt;
              &lt;version&gt;3.14&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;dom4j&lt;/groupId&gt;
              &lt;artifactId&gt;dom4j&lt;/artifactId&gt;
              &lt;version&gt;1.6.1&lt;/version&gt;
          &lt;/dependency&gt;        
          &lt;dependency&gt;
             &lt;groupId&gt;org.testng&lt;/groupId&gt;
             &lt;artifactId&gt;testng&lt;/artifactId&gt;                           
             &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.arquillian.testng&lt;/groupId&gt;
              &lt;artifactId&gt;arquillian-testng-container&lt;/artifactId&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;       
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.shrinkwrap.resolver&lt;/groupId&gt;
              &lt;artifactId&gt;shrinkwrap-resolver-api&lt;/artifactId&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;       
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.shrinkwrap.resolver&lt;/groupId&gt;
              &lt;artifactId&gt;shrinkwrap-resolver-api-maven&lt;/artifactId&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.shrinkwrap.resolver&lt;/groupId&gt;
              &lt;artifactId&gt;shrinkwrap-resolver-api-maven-archive&lt;/artifactId&gt;
              &lt;scope&gt;test&lt;/scope&gt;        
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.shrinkwrap.resolver&lt;/groupId&gt;
              &lt;artifactId&gt;shrinkwrap-resolver-impl-maven-archive&lt;/artifactId&gt;
              &lt;scope&gt;test&lt;/scope&gt;        
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.eu.ingwar.tools&lt;/groupId&gt;
              &lt;artifactId&gt;arquillian-suite-extension&lt;/artifactId&gt;         
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;       
          &lt;dependency&gt;
              &lt;groupId&gt;commons-io&lt;/groupId&gt;
              &lt;artifactId&gt;commons-io&lt;/artifactId&gt;
              &lt;version&gt;2.2&lt;/version&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.opencsv&lt;/groupId&gt;
              &lt;artifactId&gt;opencsv&lt;/artifactId&gt;
              &lt;version&gt;3.7&lt;/version&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;              
      &lt;/dependencies&gt;
      &lt;build&gt;
          &lt;plugins&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
                  &lt;artifactId&gt;maven-compiler-plugin&lt;/artifactId&gt;
                  &lt;version&gt;2.3.2&lt;/version&gt;
                  &lt;configuration&gt;
                      &lt;source&gt;1.7&lt;/source&gt;
                      &lt;target&gt;1.7&lt;/target&gt;
                  &lt;/configuration&gt;
              &lt;/plugin&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
                  &lt;artifactId&gt;maven-ejb-plugin&lt;/artifactId&gt;
                  &lt;version&gt;2.3&lt;/version&gt;
                  &lt;configuration&gt;
                      &lt;ejbVersion&gt;3.1&lt;/ejbVersion&gt;
                      &lt;archive&gt;
                          &lt;manifestEntries&gt;
                            &lt;Dependencies&gt;org.infinispan export&lt;/Dependencies&gt;
                          &lt;/manifestEntries&gt; 
                      &lt;/archive&gt;
                  &lt;/configuration&gt;
              &lt;/plugin&gt;       
          &lt;/plugins&gt;
      &lt;/build&gt;
  &lt;/project&gt;
  </code></pre>
  
  <p>Web pom.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"&gt;
      &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
      &lt;parent&gt;
          &lt;artifactId&gt;xy-portal&lt;/artifactId&gt;
          &lt;groupId&gt;com.xy&lt;/groupId&gt;
          &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
      &lt;/parent&gt;
  
      &lt;artifactId&gt;xy-portal-web&lt;/artifactId&gt;
      &lt;version&gt;${project.version}&lt;/version&gt;
      &lt;packaging&gt;war&lt;/packaging&gt;
  
      &lt;name&gt;xy-portal-web&lt;/name&gt;
  
      &lt;properties&gt;
          &lt;endorsed.dir&gt;${project.build.directory}/endorsed&lt;/endorsed.dir&gt;
          &lt;project.build.sourceEncoding&gt;UTF-8&lt;/project.build.sourceEncoding&gt;
      &lt;/properties&gt;
  
      &lt;dependencies&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.apache.poi&lt;/groupId&gt;
              &lt;artifactId&gt;poi&lt;/artifactId&gt;
              &lt;version&gt;3.14&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.apache.poi&lt;/groupId&gt;
              &lt;artifactId&gt;poi-ooxml&lt;/artifactId&gt;
              &lt;version&gt;3.14&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.apache.poi&lt;/groupId&gt;
              &lt;artifactId&gt;poi-ooxml-schemas&lt;/artifactId&gt;
              &lt;version&gt;3.14&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;dom4j&lt;/groupId&gt;
              &lt;artifactId&gt;dom4j&lt;/artifactId&gt;
              &lt;version&gt;1.6.1&lt;/version&gt;
          &lt;/dependency&gt;
  
          &lt;dependency&gt;
              &lt;groupId&gt;org.primefaces.themes&lt;/groupId&gt;
              &lt;artifactId&gt;all-themes&lt;/artifactId&gt;
              &lt;version&gt;1.0.10&lt;/version&gt;
          &lt;/dependency&gt;
  
          &lt;dependency&gt;
              &lt;groupId&gt;org.primefaces&lt;/groupId&gt;
              &lt;artifactId&gt;primefaces&lt;/artifactId&gt;
              &lt;version&gt;5.2&lt;/version&gt;
          &lt;/dependency&gt;
  
          &lt;dependency&gt;
              &lt;groupId&gt;org.omnifaces&lt;/groupId&gt;
              &lt;artifactId&gt;omnifaces&lt;/artifactId&gt;
              &lt;version&gt;1.8.1&lt;/version&gt;
          &lt;/dependency&gt;
  
          &lt;dependency&gt;
              &lt;groupId&gt;org.primefaces.extensions&lt;/groupId&gt;
              &lt;artifactId&gt;primefaces-extensions&lt;/artifactId&gt;
              &lt;version&gt;3.2.0&lt;/version&gt;
          &lt;/dependency&gt;
  
          &lt;dependency&gt;
              &lt;groupId&gt;org.webjars&lt;/groupId&gt;
              &lt;artifactId&gt;font-awesome&lt;/artifactId&gt;
              &lt;version&gt;4.6.1&lt;/version&gt;
          &lt;/dependency&gt;       
  
          &lt;dependency&gt;
              &lt;groupId&gt;commons-fileupload&lt;/groupId&gt;
              &lt;artifactId&gt;commons-fileupload&lt;/artifactId&gt;
              &lt;version&gt;1.3&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;commons-io&lt;/groupId&gt;
              &lt;artifactId&gt;commons-io&lt;/artifactId&gt;
              &lt;version&gt;2.2&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;${project.groupId}&lt;/groupId&gt;
              &lt;artifactId&gt;xy-client&lt;/artifactId&gt;
              &lt;version&gt;${project.version}&lt;/version&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
              &lt;exclusions&gt;                
                  &lt;exclusion&gt;
                      &lt;groupId&gt;org.hibernate&lt;/groupId&gt;
                      &lt;artifactId&gt;hibernate-validator&lt;/artifactId&gt;
                  &lt;/exclusion&gt;
              &lt;/exclusions&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;${project.groupId}&lt;/groupId&gt;
              &lt;artifactId&gt;xy-portal-ejb&lt;/artifactId&gt;
              &lt;version&gt;${project.version}&lt;/version&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;${project.groupId}&lt;/groupId&gt;
              &lt;artifactId&gt;xy-datamodel&lt;/artifactId&gt;
              &lt;version&gt;${project.version}&lt;/version&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
              &lt;exclusions&gt;
                  &lt;exclusion&gt;
                      &lt;groupId&gt;javax.validation&lt;/groupId&gt;
                      &lt;artifactId&gt;validation-api&lt;/artifactId&gt;
                  &lt;/exclusion&gt;
                  &lt;exclusion&gt;
                      &lt;groupId&gt;org.hibernate&lt;/groupId&gt;
                      &lt;artifactId&gt;hibernate-validator&lt;/artifactId&gt;
                  &lt;/exclusion&gt;
                  &lt;exclusion&gt;
                      &lt;groupId&gt;org.hibernate&lt;/groupId&gt;
                      &lt;artifactId&gt;hibernate-jpamodelgen&lt;/artifactId&gt;
                  &lt;/exclusion&gt;
              &lt;/exclusions&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.resteasy&lt;/groupId&gt;
              &lt;artifactId&gt;resteasy-jaxb-provider&lt;/artifactId&gt;
              &lt;version&gt;2.3.1.GA&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.resteasy&lt;/groupId&gt;
              &lt;artifactId&gt;resteasy-jaxrs&lt;/artifactId&gt;
              &lt;version&gt;2.3.1.GA&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.testng&lt;/groupId&gt;
              &lt;artifactId&gt;testng&lt;/artifactId&gt;
              &lt;version&gt;6.8.1&lt;/version&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.resteasy&lt;/groupId&gt;
              &lt;artifactId&gt;jaxrs-api&lt;/artifactId&gt;
              &lt;version&gt;3.0.8.Final&lt;/version&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;log4j&lt;/groupId&gt;
              &lt;artifactId&gt;log4j&lt;/artifactId&gt;
              &lt;version&gt;1.2.17&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.hibernate&lt;/groupId&gt;
              &lt;artifactId&gt;hibernate-validator&lt;/artifactId&gt;
              &lt;version&gt;5.1.2.Final&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.jboss.spec&lt;/groupId&gt;
              &lt;artifactId&gt;jboss-javaee-web-6.0&lt;/artifactId&gt;
              &lt;version&gt;3.0.3.Final&lt;/version&gt;
              &lt;type&gt;pom&lt;/type&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;junit&lt;/groupId&gt;
              &lt;artifactId&gt;junit&lt;/artifactId&gt;
              &lt;version&gt;4.8.1&lt;/version&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;jboss&lt;/groupId&gt;
              &lt;artifactId&gt;jbosssx&lt;/artifactId&gt;
              &lt;version&gt;3.2.3&lt;/version&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;jboss&lt;/groupId&gt;
              &lt;artifactId&gt;jboss-jaas&lt;/artifactId&gt;
              &lt;version&gt;3.2.3&lt;/version&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;net.glxn&lt;/groupId&gt;
              &lt;artifactId&gt;qrgen&lt;/artifactId&gt;
              &lt;version&gt;1.4&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;net.sf.barcode4j&lt;/groupId&gt;
              &lt;artifactId&gt;barcode4j-light&lt;/artifactId&gt;
              &lt;version&gt;2.0&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;jexcelapi&lt;/groupId&gt;
              &lt;artifactId&gt;jxl&lt;/artifactId&gt;
              &lt;version&gt;2.6&lt;/version&gt;
          &lt;/dependency&gt;
      &lt;/dependencies&gt;
      &lt;build&gt;
          &lt;plugins&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
                  &lt;artifactId&gt;maven-compiler-plugin&lt;/artifactId&gt;
                  &lt;version&gt;2.3.2&lt;/version&gt;
                  &lt;configuration&gt;
                      &lt;source&gt;1.7&lt;/source&gt;
                      &lt;target&gt;1.7&lt;/target&gt;
                  &lt;/configuration&gt;
              &lt;/plugin&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
                  &lt;artifactId&gt;maven-war-plugin&lt;/artifactId&gt;
                  &lt;version&gt;2.1.1&lt;/version&gt;
                  &lt;configuration&gt;
                      &lt;failOnMissingWebXml&gt;false&lt;/failOnMissingWebXml&gt;
                  &lt;/configuration&gt;
              &lt;/plugin&gt;           
          &lt;/plugins&gt;
      &lt;/build&gt;
  &lt;/project&gt;
  </code></pre>
  
  <h1>4. Exception</h1>
  
  <pre><code>Caused by: javax.faces.el.EvaluationException: java.lang.LinkageError: loader constraint violation: when resolving method "ejb.x.y.FileFormatConvertor.fromExcelToCsv(Lorg/apache/poi/ss/usermodel/Workbook;Lorg/apache/poi/ss/usermodel/Sheet;Ljava/lang/String;)[B" the class loader (instance of org/jboss/modules/ModuleClassLoader) of the current class, web.x.y.FileUploadViewAction, and the class loader (instance of org/jboss/modules/ModuleClassLoader) for resolved class, ejb.x.y.FileFormatConvertor, have different Class objects for the type Lorg/apache/poi/ss/usermodel/Workbook;Lorg/apache/poi/ss/usermodel/Sheet;Ljava/lang/String;)[B used in the signature
      at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final]
      at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) [jsf-impl-2.1.7-jbossorg-2.jar:]
      ... 36 more
  </code></pre>
  
  <p>What am I doing wrong to be getting this exception?
  So far I have done the following:
  1. Check for cyclic class path dependencies
  2. Move the ejb to web tier as managed bean (solves the problem but the bean is accessed elsewhere by other clients, making the business tier a more natural home)
  3. Searched this site for similar problem/solution trails but have found none</p>
  
  <p>Please help...</p>