CQ5 how to use external jars in custom plugins

Question

I have to create my own plugin to parse xml and do other stuff. I've created my own bundle plugin that will contain my parser class, pom.xml below:

<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">
<modelVersion>4.0.0</modelVersion>

<groupId>pl.mycompany.myproject</groupId>
<artifactId>core</artifactId>
<version>1.0.0-SNAPSHOT</version>
<packaging>bundle</packaging>

<name>core</name>
<url>http://maven.apache.org</url>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.5</source>
                <target>1.5</target>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.felix</groupId>
            <artifactId>maven-bundle-plugin</artifactId>
            <version>1.4.3</version>
            <extensions>true</extensions>
            <configuration>
                <instructions>
                    <Export-Package>pl.mycompany.myproject.page.components.*;version=${pom.version}</Export-Package>
                </instructions>
            </configuration>                
        </plugin>
    </plugins>
</build>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>3.8.1</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.day.cq.wcm</groupId>
        <artifactId>cq-wcm-api</artifactId>
        <version>5.6.4</version>
    </dependency>
    <dependency>
        <groupId>com.day.cq</groupId>
        <artifactId>cq-commons</artifactId>
        <version>5.6.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.sling</groupId>
        <artifactId>org.apache.sling.api</artifactId>
        <version>2.0.4-incubator</version>
    </dependency>
    <dependency>
        <groupId>org.apache.sling</groupId>
        <artifactId>org.apache.sling.commons.json</artifactId>
        <version>2.0.6</version>
    </dependency>
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-lang3</artifactId>
        <version>3.0.1</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>xerces</groupId>
        <artifactId>xercesImpl</artifactId>
        <version>2.9.0</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

After that I want to create class that will parse xml and I want to use org.apache.xerces package.

I've also created other bundle that contains org.apache.xerces jar and I've installed it and it is active in http://myhost.com:4502/system/console/bundles.

When I want to declare DOMParser variable in Java class in core plugin (pom.xml above):

package pl.mycompany.myproject.page.components;
import java.util.Date;
import org.apache.sling.api.resource.Resource;
import org.apache.xerces.parsers.DOMParser;
enter code here
public class EqAndSpecParser {

private Resource resource;

public EqAndSpecParser(Resource resource) {
    this.resource = resource;
}

public void checkIfNeedToUpdate(Date lastModifiedDate, String lastGenerationDate, String xmlCode) {
    try {
        DOMParser parser = new DOMParser();
        parser.parse(xmlCode);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public Resource getResource() {
    return resource;
}

public void setResource(Resource resource) {
    this.resource = resource;
}

}

Then I get error in /crx-quickstart/logs/:

FULL EXCEPTION:
org.apache.sling.api.scripting.ScriptEvaluationException: An exception occurred processing JSP page /apps/myproject/components/specifications-and-equipment/specifications-and-equipment.jsp at line 16
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:388)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.eval(DefaultSlingScript.java:171)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.service(DefaultSlingScript.java:463)
at org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:508)
at org.apache.sling.engine.impl.filter.SlingComponentFilterChain.render(SlingComponentFilterChain.java:45)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:64)
at com.day.cq.wcm.core.impl.WCMDebugFilter.doFilterWithErrorHandling(WCMDebugFilter.java:184)
at com.day.cq.wcm.core.impl.WCMDebugFilter.doFilter(WCMDebugFilter.java:151)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.wcm.core.impl.WCMComponentFilter.doFilter(WCMComponentFilter.java:244)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.engine.impl.SlingRequestProcessorImpl.processComponent(SlingRequestProcessorImpl.java:254)
at org.apache.sling.engine.impl.SlingRequestProcessorImpl.dispatchRequest(SlingRequestProcessorImpl.java:294)
at org.apache.sling.engine.impl.request.SlingRequestDispatcher.dispatch(SlingRequestDispatcher.java:216)
at org.apache.sling.engine.impl.request.SlingRequestDispatcher.include(SlingRequestDispatcher.java:103)
at com.day.cq.wcm.core.impl.WCMComponentFilter$ForwardRequestDispatcher.include(WCMComponentFilter.java:406)
at org.apache.sling.scripting.jsp.taglib.IncludeTagHandler.dispatch(IncludeTagHandler.java:49)
at org.apache.sling.scripting.jsp.taglib.AbstractDispatcherTagHandler.doEndTag(AbstractDispatcherTagHandler.java:129)
at org.apache.jsp.libs.foundation.components.parsys.parsys_jsp._jspService(parsys_jsp.java:313)
at org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:449)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.callJsp(JspScriptEngineFactory.java:241)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.access$100(JspScriptEngineFactory.java:86)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:441)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:361)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.eval(DefaultSlingScript.java:171)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.service(DefaultSlingScript.java:463)
at org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:508)
at org.apache.sling.engine.impl.filter.SlingComponentFilterChain.render(SlingComponentFilterChain.java:45)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:64)
at com.day.cq.wcm.core.impl.WCMDebugFilter.doFilterWithErrorHandling(WCMDebugFilter.java:184)
at com.day.cq.wcm.core.impl.WCMDebugFilter.doFilter(WCMDebugFilter.java:151)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.wcm.core.impl.WCMComponentFilter.doFilter(WCMComponentFilter.java:244)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.engine.impl.SlingRequestProcessorImpl.processComponent(SlingRequestProcessorImpl.java:254)
at org.apache.sling.engine.impl.SlingRequestProcessorImpl.dispatchRequest(SlingRequestProcessorImpl.java:294)
at org.apache.sling.engine.impl.request.SlingRequestDispatcher.dispatch(SlingRequestDispatcher.java:216)
at org.apache.sling.engine.impl.request.SlingRequestDispatcher.include(SlingRequestDispatcher.java:103)
at com.day.cq.wcm.core.impl.WCMComponentFilter$ForwardRequestDispatcher.include(WCMComponentFilter.java:406)
at com.day.cq.wcm.tags.IncludeTag.includeResource(IncludeTag.java:224)
at com.day.cq.wcm.tags.IncludeTag.doEndTag(IncludeTag.java:91)
at org.apache.jsp.apps.myproject.components.contentpage_002d100_002d20_002d60_002d20.content_jsp._jspx_meth_cq_005finclude_005f3(content_jsp.java:276)
at org.apache.jsp.apps.myproject.components.contentpage_002d100_002d20_002d60_002d20.content_jsp._jspService(content_jsp.java:174)
at org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:449)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.callJsp(JspScriptEngineFactory.java:241)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.access$100(JspScriptEngineFactory.java:86)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:441)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:361)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.eval(DefaultSlingScript.java:171)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.service(DefaultSlingScript.java:463)
at com.day.cq.wcm.tags.IncludeTag.includeScript(IncludeTag.java:167)
at com.day.cq.wcm.tags.IncludeTag.doEndTag(IncludeTag.java:87)
at org.apache.jsp.apps.myproject.components.page.body_jsp._jspx_meth_cq_005finclude_005f2(body_jsp.java:308)
at org.apache.jsp.apps.myproject.components.page.body_jsp._jspService(body_jsp.java:228)
at org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:449)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.callJsp(JspScriptEngineFactory.java:241)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.access$100(JspScriptEngineFactory.java:86)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:441)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:361)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.eval(DefaultSlingScript.java:171)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.service(DefaultSlingScript.java:463)
at com.day.cq.wcm.tags.IncludeTag.includeScript(IncludeTag.java:167)
at com.day.cq.wcm.tags.IncludeTag.doEndTag(IncludeTag.java:87)
at org.apache.jsp.libs.foundation.components.page.page_jsp._jspx_meth_cq_005finclude_005f1(page_jsp.java:207)
at org.apache.jsp.libs.foundation.components.page.page_jsp._jspService(page_jsp.java:161)
at org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:449)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.callJsp(JspScriptEngineFactory.java:241)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.access$100(JspScriptEngineFactory.java:86)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:441)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:361)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.eval(DefaultSlingScript.java:171)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.service(DefaultSlingScript.java:463)
at org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:508)
at org.apache.sling.engine.impl.filter.SlingComponentFilterChain.render(SlingComponentFilterChain.java:45)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:64)
at com.day.cq.wcm.core.impl.WCMDebugFilter.doFilterWithErrorHandling(WCMDebugFilter.java:184)
at com.day.cq.wcm.core.impl.WCMDebugFilter.doFilter(WCMDebugFilter.java:151)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.wcm.core.impl.WCMComponentFilter.doFilter(WCMComponentFilter.java:244)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.engine.impl.SlingRequestProcessorImpl.processComponent(SlingRequestProcessorImpl.java:254)
at org.apache.sling.engine.impl.SlingRequestProcessorImpl.dispatchRequest(SlingRequestProcessorImpl.java:294)
at org.apache.sling.engine.impl.request.SlingRequestDispatcher.dispatch(SlingRequestDispatcher.java:216)
at org.apache.sling.engine.impl.request.SlingRequestDispatcher.include(SlingRequestDispatcher.java:103)
at com.day.cq.wcm.core.impl.WCMComponentFilter$ForwardRequestDispatcher.include(WCMComponentFilter.java:406)
at org.apache.jsp.libs.foundation.components.primary.cq.Page.Page_jsp._jspService(Page_jsp.java:106)
at org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:449)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.callJsp(JspScriptEngineFactory.java:241)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.access$100(JspScriptEngineFactory.java:86)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:441)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:361)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.eval(DefaultSlingScript.java:171)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.service(DefaultSlingScript.java:463)
at org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:508)
at org.apache.sling.engine.impl.filter.SlingComponentFilterChain.render(SlingComponentFilterChain.java:45)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:64)
at com.day.cq.wcm.core.impl.WCMDebugFilter.doFilter(WCMDebugFilter.java:148)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.wcm.core.impl.WCMComponentFilter.filterRootInclude(WCMComponentFilter.java:333)
at com.day.cq.wcm.core.impl.WCMComponentFilter.doFilter(WCMComponentFilter.java:160)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.engine.impl.SlingRequestProcessorImpl.processComponent(SlingRequestProcessorImpl.java:254)
at org.apache.sling.engine.impl.filter.RequestSlingFilterChain.render(RequestSlingFilterChain.java:49)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:64)
at com.day.cq.wcm.core.impl.warp.TimeWarpFilter.doFilter(TimeWarpFilter.java:106)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.wcm.mobile.core.impl.redirect.RedirectFilter.doFilter(RedirectFilter.java:290)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.engine.impl.debug.RequestProgressTrackerLogFilter.doFilter(RequestProgressTrackerLogFilter.java:59)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.wcm.foundation.forms.impl.FormsHandlingServlet.doFilter(FormsHandlingServlet.java:220)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.theme.impl.ThemeResolverFilter.doFilter(ThemeResolverFilter.java:76)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.adobe.granite.optout.impl.OptOutFilter.doFilter(OptOutFilter.java:74)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.wcm.core.impl.WCMRequestFilter.doFilter(WCMRequestFilter.java:90)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at com.day.cq.wcm.designimporter.CanvasPageDeleteRequestFilter.doFilter(CanvasPageDeleteRequestFilter.java:87)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.rewriter.impl.RewriterFilter.doFilter(RewriterFilter.java:83)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.i18n.impl.I18NFilter.doFilter(I18NFilter.java:127)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.bgservlets.impl.BackgroundServletStarterFilter.doFilter(BackgroundServletStarterFilter.java:135)
at org.apache.sling.engine.impl.filter.AbstractSlingFilterChain.doFilter(AbstractSlingFilterChain.java:60)
at org.apache.sling.engine.impl.SlingRequestProcessorImpl.processRequest(SlingRequestProcessorImpl.java:151)
at org.apache.sling.engine.impl.SlingMainServlet.service(SlingMainServlet.java:206)
at org.apache.felix.http.base.internal.handler.ServletHandler.doHandle(ServletHandler.java:96)
at org.apache.felix.http.base.internal.handler.ServletHandler.handle(ServletHandler.java:79)
at org.apache.felix.http.base.internal.dispatch.ServletPipeline.handle(ServletPipeline.java:42)
at org.apache.felix.http.base.internal.dispatch.InvocationFilterChain.doFilter(InvocationFilterChain.java:49)
at org.apache.felix.http.base.internal.dispatch.HttpFilterChain.doFilter(HttpFilterChain.java:33)
at org.apache.sling.i18n.impl.I18NFilter.doFilter(I18NFilter.java:127)
at org.apache.felix.http.base.internal.handler.FilterHandler.doHandle(FilterHandler.java:88)
at org.apache.felix.http.base.internal.handler.FilterHandler.handle(FilterHandler.java:76)
at org.apache.felix.http.base.internal.dispatch.InvocationFilterChain.doFilter(InvocationFilterChain.java:47)
at org.apache.felix.http.base.internal.dispatch.HttpFilterChain.doFilter(HttpFilterChain.java:33)
at com.adobe.granite.license.impl.LicenseCheckFilter.doFilter(LicenseCheckFilter.java:179)
at org.apache.felix.http.base.internal.handler.FilterHandler.doHandle(FilterHandler.java:88)
at org.apache.felix.http.base.internal.handler.FilterHandler.handle(FilterHandler.java:76)
at org.apache.felix.http.base.internal.dispatch.InvocationFilterChain.doFilter(InvocationFilterChain.java:47)
at org.apache.felix.http.base.internal.dispatch.HttpFilterChain.doFilter(HttpFilterChain.java:33)
at org.apache.sling.security.impl.ReferrerFilter.doFilter(ReferrerFilter.java:259)
at org.apache.felix.http.base.internal.handler.FilterHandler.doHandle(FilterHandler.java:88)
at org.apache.felix.http.base.internal.handler.FilterHandler.handle(FilterHandler.java:76)
at org.apache.felix.http.base.internal.dispatch.InvocationFilterChain.doFilter(InvocationFilterChain.java:47)
at org.apache.felix.http.base.internal.dispatch.HttpFilterChain.doFilter(HttpFilterChain.java:33)
at org.apache.felix.http.sslfilter.internal.SslFilter.doFilter(SslFilter.java:55)
at org.apache.felix.http.base.internal.handler.FilterHandler.doHandle(FilterHandler.java:88)
at org.apache.felix.http.base.internal.handler.FilterHandler.handle(FilterHandler.java:76)
at org.apache.felix.http.base.internal.dispatch.InvocationFilterChain.doFilter(InvocationFilterChain.java:47)
at org.apache.felix.http.base.internal.dispatch.HttpFilterChain.doFilter(HttpFilterChain.java:33)
at org.apache.sling.engine.impl.log.RequestLoggerFilter.doFilter(RequestLoggerFilter.java:75)
at org.apache.felix.http.base.internal.handler.FilterHandler.doHandle(FilterHandler.java:88)
at org.apache.felix.http.base.internal.handler.FilterHandler.handle(FilterHandler.java:76)
at org.apache.felix.http.base.internal.dispatch.InvocationFilterChain.doFilter(InvocationFilterChain.java:47)
at org.apache.felix.http.base.internal.dispatch.HttpFilterChain.doFilter(HttpFilterChain.java:33)
at org.apache.felix.http.base.internal.dispatch.FilterPipeline.dispatch(FilterPipeline.java:48)
at org.apache.felix.http.base.internal.dispatch.Dispatcher.dispatch(Dispatcher.java:39)
at org.apache.felix.http.base.internal.DispatcherServlet.service(DispatcherServlet.java:67)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at com.day.j2ee.servletengine.ServletRuntimeEnvironment.service(ServletRuntimeEnvironment.java:250)
at com.day.j2ee.servletengine.RequestDispatcherImpl.doFilter(RequestDispatcherImpl.java:321)
at com.day.j2ee.servletengine.RequestDispatcherImpl.service(RequestDispatcherImpl.java:340)
at com.day.j2ee.servletengine.RequestDispatcherImpl.service(RequestDispatcherImpl.java:383)
at com.day.j2ee.servletengine.ServletHandlerImpl.process(ServletHandlerImpl.java:360)
at com.day.j2ee.servletengine.HttpListener$Worker.run(HttpListener.java:644)
at java.lang.Thread.run(Unknown Source)
Caused by: org.apache.sling.api.SlingException: An exception occurred processing JSP page /apps/myproject/components/specifications-and-equipment/specifications-and-equipment.jsp at line 16
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.handleJspExceptionInternal(JspServletWrapper.java:683)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:608)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:525)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:449)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.callJsp(JspScriptEngineFactory.java:241)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory.access$100(JspScriptEngineFactory.java:86)
at org.apache.sling.scripting.jsp.JspScriptEngineFactory$JspScriptEngine.eval(JspScriptEngineFactory.java:441)
at org.apache.sling.scripting.core.impl.DefaultSlingScript.call(DefaultSlingScript.java:361)
... 183 more
Caused by: java.lang.NoClassDefFoundError: org/apache/xerces/parsers/DOMParser
at org.apache.jsp.apps.myproject.components.specifications_002dand_002dequipment.specifications_002dand_002dequipment_jsp._jspService(specifications_002dand_002dequipment_jsp.java:165)
at org.apache.sling.scripting.jsp.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.apache.sling.scripting.jsp.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:502)
... 188 more
Caused by: java.lang.ClassNotFoundException: org.apache.xerces.parsers.DOMParser not found by pl.mycompany.myproject.core [291]
at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1499)
at org.apache.felix.framework.BundleWiringImpl.access$400(BundleWiringImpl.java:75)
at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1882)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 192 more

DOMParser is just example class that I want to use. In my project I will need to use external jars from the other providers, that is just POC. The main question is: How to use external jars in CQ5? How to install them into CQ that all custom plugins would use these jars?

When I changed xerces dependency to

<dependency>
    <groupId>xerces</groupId>
    <artifactId>xercesImpl</artifactId>
    <version>2.9.0</version>
    <scope>compile</scope>
</dependency>

and I added <Embed-Dependency>xercesImpl;scope=compile</Embed-Dependency> now I get error like:

25.09.2013 11:15:49.206 *INFO* [JcrInstaller.1]
org.apache.sling.installer.provider.jcr.impl.JcrInstaller Registering resource with OSGi installer: [InstallableResource, priority=200, id=/apps/myproject/install/core-1.0.0-SNAPSHOT.jar]
25.09.2013 11:15:49.231 *INFO* [OsgiInstallerImpl] pl.mycompany.myproject.core BundleEvent UNRESOLVED
25.09.2013 11:15:49.231 *INFO* [OsgiInstallerImpl] pl.mycompany.myproject.core BundleEvent UPDATED
25.09.2013 11:15:49.233 *INFO* [OsgiInstallerImpl] org.apache.sling.audit.osgi.installer Updated bundle pl.mycompany.myproject.core [291] from resource TaskResource(url=jcrinstall:/apps/myproject/install/core-1.0.0-SNAPSHOT.jar, entity=bundle:pl.mycompany.myproject.core, state=INSTALL, attributes=[org.apache.sling.installer.api.tasks.ResourceTransformer=:50:16:, Bundle-SymbolicName=pl.mycompany.myproject.core, Bundle-Version=1.0.0.SNAPSHOT], digest=1380100548768)
25.09.2013 11:15:49.234 *INFO* [OsgiInstallerImpl] org.apache.sling.audit.osgi.installer Refreshing 1 bundles: [pl.mycompany.myproject.core [291]]
25.09.2013 11:15:49.234 *INFO* [OsgiInstallerImpl] org.apache.sling.audit.osgi.installer Waiting up to 90 seconds for bundles refresh
25.09.2013 11:15:49.234 *INFO* [OsgiInstallerImpl] org.apache.sling.audit.osgi.installer Done refreshing 1 bundles
25.09.2013 11:15:49.234 *INFO* [FelixDispatchQueue] org.apache.felix.framework FrameworkEvent PACKAGES REFRESHED
25.09.2013 11:15:49.235 *INFO* [FelixDispatchQueue] org.apache.felix.framework FrameworkEvent PACKAGES REFRESHED
25.09.2013 11:15:49.235 *INFO* [OsgiInstallerImpl] org.apache.sling.installer.core.impl.tasks.BundleStartTask Could not start bundle pl.mycompany.myproject.core [291]. Reason: org.osgi.framework.BundleException: Unresolved constraint in bundle pl.mycompany.myproject.core [291]: Unable to resolve 291.34: missing requirement [291.34] osgi.wiring.package; (osgi.wiring.package=org.apache.xml.resolver). Will retry.
25.09.2013 11:15:49.235 *INFO* [OsgiInstallerImpl] org.apache.sling.installer.core.impl.tasks.RestartActiveBundlesTask Unable to start bundle pl.mycompany.myproject.core [291] : Unresolved constraint in bundle pl.mycompany.myproject.core [291]: Unable to resolve 291.34: missing requirement [291.34] osgi.wiring.package; (osgi.wiring.package=org.apache.xml.resolver)
25.09.2013 11:15:49.248 *INFO* [OsgiInstallerImpl] org.apache.sling.installer.core.impl.tasks.BundleStartTask Could not start bundle pl.mycompany.myproject.core [291]. Reason: org.osgi.framework.BundleException: Unresolved constraint in bundle pl.mycompany.myproject.core [291]: Unable to resolve 291.34: missing requirement [291.34] osgi.wiring.package; (osgi.wiring.package=org.apache.xml.resolver). Will retry.
25.09.2013 11:15:49.249 *INFO* [OsgiInstallerImpl] org.apache.sling.installer.core.impl.tasks.RestartActiveBundlesTask Unable to start bundle pl.mycompany.myproject.core [291] : Unresolved constraint in bundle pl.mycompany.myproject.core [291]: Unable to resolve 291.34: missing requirement [291.34] osgi.wiring.package; (osgi.wiring.package=org.apache.xml.resolver)

Answer 1

Including external JARs to your bundle

This part of your pom.xml:

<dependency>
    <groupId>xerces</groupId>
    <artifactId>xercesImpl</artifactId>
    <version>2.9.0</version>
    <scope>provided</scope>
</dependency>

defines xerces as provided dependency, eg. one already existing in the CQ. If you'd like to embed this dependency, change it scope to compile and use <embed-dependency> option for the Maven bundle plugin, like:

<configuration>
    <instructions>
        <Export-Package>pl.mycompany.myproject.page.components.*;version=${pom.version}</Export-Package>
        <Embed-Dependency>xercesImpl;scope=compile</Embed-Dependency>
    </instructions>
</configuration>                

Also, it's a good idea to add provided scope to all dependencies which are actually included within the CQ (like cq-wcm-api, etc).

Parsing XMLs in CQ5

Above is a direct answer to your question ("how to use external JAR"). However, in this particular case, I don't think you should include the xerces library, as it already exists in the JDK. Try to remove the xerces dependency and use javax.xml.parsers API:

import javax.xml.parsers.*;
...
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance()
DocumentBuilder builder = factory.newDocumentBuilder()
builder.parse(new ByteArrayInputStream(xmlCode.getBytes()));