Call ant inside a eclipse plugin - eclipse

Question

I have a Eclipse Plugin and I need to call ant inside of that plugin to make some stuffs, like run junit test and get the coverage of that test (using jacoco plugin for this purpose)...
My build.xml
<project name="Calculadora" default="rebuild" basedir="." xmlns:jacoco="antlib:org.jacoco.ant">
<property name="src" location="./src"/>
<property name="bin.dir" location="./bin"/>
<property name="bin.report.dir" location="${bin.dir}/report"/>
<property name="bin.exec.file" location="${bin.dir}/jacoco.exec"/>
<property name="junit.out.dir" location="${bin.report.dir}/junit/xml"/>
<taskdef uri="antlib:org.jacoco.ant" resource="org/jacoco/ant/antlib.xml">
<classpath path="/tmp/jacocoant4002041518230825590.jar"/>
</taskdef>
<path id="classpath">
<pathelement location="${bin.dir}"/>
<pathelement location="${src}"/>
<pathelement location="/usr/lib/eclipse/plugins/org.junit4_4.5.0.v20090824/junit.jar"/>
</path>
<target name="clean">
<mkdir dir="${bin.report.dir}"/>
<mkdir dir="${junit.out.dir}"/>
</target>
<target name="test" depends="clean">
<jacoco:coverage destfile="${bin.exec.file}">
<junit fork="true" forkmode="once">
<classpath refid="classpath"/>
<formatter type="xml" usefile="true"/>
<test name="functions.test.ReadFile" todir="${junit.out.dir}"/>
</junit>
</jacoco:coverage>
</target>
<target name="report" depends="test">
<jacoco:report>
<executiondata>
<file file="${bin.exec.file}"/>
</executiondata>
<structure name="">
<classfiles>
<fileset dir="${bin.dir}"/>
</classfiles>
<sourcefiles encoding="UTF-8">
<fileset dir="${src}"/>
</sourcefiles>
</structure>
<xml destfile="${bin.report.dir}/report.xml"/>
</jacoco:report>
<junitreport todir="${junit.out.dir}">
<fileset dir="${junit.out.dir}">
<include name="TEST-*.xml"/>
</fileset>
</junitreport>
</target>
<target name="rebuild" depends="clean,test,report"/>
</project>
The code to call Ant in Java:
// Creates a new Project object
Project p = new Project();
p.setUserProperty("ant.file", buildFile.getAbsolutePath());
p.init();
ProjectHelper helper = ProjectHelper.getProjectHelper();
p.addReference("ant.projectHelper", helper);
helper.parse(p, buildFile);
DefaultLogger consoleLogger = new DefaultLogger();
consoleLogger.setErrorPrintStream(System.err);
consoleLogger.setOutputPrintStream(System.out);
consoleLogger.setMessageOutputLevel(Project.MSG_INFO);
p.addBuildListener(consoleLogger);
p.executeTarget(p.getDefaultTarget());
But when I run my plugin i get this error:
build.xml:34: java.lang.ClassNotFoundException:
org.apache.tools.ant.taskdefs.optional.junit.JUnitTaskMirrorImpl at
org.apache.tools.ant.taskdefs.optional.junit.JUnitTask.createMirror(JUnitTask.java:708)
at
org.apache.tools.ant.taskdefs.optional.junit.JUnitTask.setupJUnitDelegate(JUnitTask.java:745)
at
org.apache.tools.ant.taskdefs.optional.junit.JUnitTask.execute(JUnitTask.java:755)
at
org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
at org.jacoco.ant.CoverageTask.execute(CoverageTask.java:95) at
org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616) at
org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
at org.apache.tools.ant.Task.perform(Task.java:348) at
org.apache.tools.ant.Target.execute(Target.java:390) at
org.apache.tools.ant.Target.performTasks(Target.java:411) at
org.apache.tools.ant.Project.executeSortedTargets(Project.java:1360)
at org.apache.tools.ant.Project.executeTarget(Project.java:1329)
Caused by: java.lang.ClassNotFoundException:
org.apache.tools.ant.taskdefs.optional.junit.JUnitTaskMirrorImpl at
org.apache.tools.ant.AntClassLoader.findClassInComponents(AntClassLoader.java:1386)
at
org.apache.tools.ant.AntClassLoader.findClass(AntClassLoader.java:1336)
at
org.apache.tools.ant.util.SplitClassLoader.loadClass(SplitClassLoader.java:52)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266) at
org.apache.tools.ant.taskdefs.optional.junit.JUnitTask.createMirror(JUnitTask.java:701)
... 19 more
What's happening? What I am doing wrong?
Thanks in advance