When I build with ant my project that uses libgdx, I get a strange error. It says that a class com.google.gwt.dom.client.ImageElement is not found, but it isn't used at all in the code. How can I find what makes this class necessary? Even searching over the whole project doesn't give any results. It says that error is at PixmapTextureAtlas.java:16 (class source), but there is no code that uses that ImageElement class. Adding the library containing com.google.gwt.dom.client.ImageElement class helps, of course, but I'd like to figure out why this class in needed.

Here is the place in ant log that tells of the actual error:

Compiling 3 source files to /home/suseika/Projects/tendiwa/client/bin
/home/suseika/Projects/tendiwa/client/src/org/tendiwa/client/PixmapTextureAtlas.java:16: error: cannot access ImageElement
class file for com.google.gwt.dom.client.ImageElement not found

Here is the whole ant log:

 /usr/lib/jvm/java-7-oracle/bin/java -Xmx128m -Xss2m -Dant.home=/opt/intellijidea/lib/ant -Dant.library.dir=/opt/intellijidea/lib/ant/lib -Dfile.encoding=UTF-8 -classpath /opt/intellijidea/lib/ant/lib/ant-apache-regexp.jar:/opt/intellijidea/lib/ant/lib/ant-swing.jar:/opt/intellijidea/lib/ant/lib/ant-apache-xalan2.jar:/opt/intellijidea/lib/ant/lib/ant-jdepend.jar:/opt/intellijidea/lib/ant/lib/ant-apache-resolver.jar:/opt/intellijidea/lib/ant/lib/ant-jsch.jar:/opt/intellijidea/lib/ant/lib/ant.jar:/opt/intellijidea/lib/ant/lib/ant-testutil.jar:/opt/intellijidea/lib/ant/lib/ant-launcher.jar:/opt/intellijidea/lib/ant/lib/ant-apache-bsf.jar:/opt/intellijidea/lib/ant/lib/ant-commons-logging.jar:/opt/intellijidea/lib/ant/lib/ant-netrexx.jar:/opt/intellijidea/lib/ant/lib/ant-junit.jar:/opt/intellijidea/lib/ant/lib/ant-commons-net.jar:/opt/intellijidea/lib/ant/lib/ant-apache-bcel.jar:/opt/intellijidea/lib/ant/lib/ant-antlr.jar:/opt/intellijidea/lib/ant/lib/ant-apache-log4j.jar:/opt/intellijidea/lib/ant/lib/ant-jai.jar:/opt/intellijidea/lib/ant/lib/ant-apache-oro.jar:/opt/intellijidea/lib/ant/lib/ant-jmf.jar:/opt/intellijidea/lib/ant/lib/ant-javamail.jar:/usr/lib/jvm/java-7-oracle/lib/tools.jar:/opt/intellijidea/lib/idea_rt.jar com.intellij.rt.ant.execution.AntMain2 -logger com.intellij.rt.ant.execution.IdeaAntLogger2 -inputhandler com.intellij.rt.ant.execution.IdeaInputHandler -buildfile /home/suseika/Projects/tendiwa/client/build.xml jar
build.xml
property
path
description
compile
ant
property
property
property
description
compile
mkdir
javac
jar
ant
property
description
_core_src_available
available
ontology
antcall
property
description
_core_src_available
available
_build_core
ant
property
property
compile
echo
/home/suseika/Projects/tendiwa/client
mkdir
javac
jar
jar
Building jar: /home/suseika/Projects/tendiwa/MainModule.jar
description
tempfile
mkdir
Created dir: /tmp/tendiwa373148820
unjar
Expanding: /home/suseika/Projects/tendiwa/MainModule.jar into /tmp/tendiwa373148820
Expanding: /home/suseika/Projects/tendiwa/tendiwa-backend.jar into /tmp/tendiwa373148820
Expanding: /home/suseika/Projects/tendiwa/tendiwa-ontology.jar into /tmp/tendiwa373148820
copy
Copying 1 file to /tmp/tendiwa373148820
java
Created item short_sword
Created item short_bow
Created item bucket
Created item boot
Created item steel_morningstar
Created item rifle_ammo
Created item handAxe
Created item iron_armor
Created item steel_mace
Created item jacket
Created item fedora
Created item wooden_arrow
Saving sources to /tmp/tendiwa373148820/ontology/src
tendiwa/resources/SoundTypes.java
tendiwa/resources/CharacterTypes.java
tendiwa/resources/ObjectTypes.java
tendiwa/resources/FloorTypes.java
tendiwa/resources/ItemTypes.java
tendiwa/resources/MaterialTypes.java
mkdir
mkdir
mkdir
Created dir: /tmp/tendiwa373148820/ontology/bin
javac
jar
Building jar: /home/suseika/Projects/tendiwa/tendiwa-ontology.jar
echo
Resources source code generated
ant
property
property
compile
echo
/home/suseika/Projects/tendiwa/client
mkdir
javac
jar
jar
jar
Building jar: /home/suseika/Projects/tendiwa/MainModule.jar
mkdir
javac
/home/suseika/Projects/tendiwa/client/build.xml:25: Compile failed; see the compiler error output for details.
    at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1150)
    at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:912)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    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:1399)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    at org.apache.tools.ant.Main.runBuild(Main.java:809)
    at org.apache.tools.ant.Main.startAnt(Main.java:217)
    at org.apache.tools.ant.Main.start(Main.java:180)
    at org.apache.tools.ant.Main.main(Main.java:268)
    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:606)
    at com.intellij.rt.ant.execution.AntMain2.main(AntMain2.java:30)
/home/suseika/Projects/tendiwa/client/build.xml (25:46)'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
Compiling 3 source files to /home/suseika/Projects/tendiwa/client/bin
/home/suseika/Projects/tendiwa/client/src/org/tendiwa/client/PixmapTextureAtlas.java:16: error: cannot access ImageElement
class file for com.google.gwt.dom.client.ImageElement not found
1 error
/home/suseika/Projects/tendiwa/client/build.xml:25: Compile failed; see the compiler error output for details.
    at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1150)
    at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:912)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    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:1399)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    at org.apache.tools.ant.Main.runBuild(Main.java:809)
    at org.apache.tools.ant.Main.startAnt(Main.java:217)
    at org.apache.tools.ant.Main.start(Main.java:180)
    at org.apache.tools.ant.Main.main(Main.java:268)
    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:606)
    at com.intellij.rt.ant.execution.AntMain2.main(AntMain2.java:30)
/home/suseika/Projects/tendiwa/client/build.xml:25: Compile failed; see the compiler error output for details.
    at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1150)
    at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:912)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    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:1399)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    at org.apache.tools.ant.Main.runBuild(Main.java:809)
    at org.apache.tools.ant.Main.startAnt(Main.java:217)
    at org.apache.tools.ant.Main.start(Main.java:180)
    at org.apache.tools.ant.Main.main(Main.java:268)
    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:606)
    at com.intellij.rt.ant.execution.AntMain2.main(AntMain2.java:30)

Ant build completed with 3 errors one warning in 4s at 10/30/13 3:09 AM

Here is a part of ant file where this error appears:

<path id="tendiwa.jars">
    <fileset dir="../libs">
        <include name="**/*.jar"/>
    </fileset>
    <pathelement path="../tendiwa-backend.jar"/>
    <pathelement path="../tendiwa-ontology.jar"/>
    <!--<fileset dir="/usr/share/java" includes="gwt*.jar"/>-->
</path>

<target name="compile">
    <ant dir="../MainModule" target="jar"/>
    <mkdir dir="bin"/>
    <javac destdir="bin" failonerror="true">
        <classpath>
            <path refid="tendiwa.jars"/>

            <!--temporary-->
            <pathelement path="../tendiwa-ontology.jar"/>
            <!--temporary-->
            <pathelement path="../MainModule.jar"/>
            <fileset dir="../libs" includes="**/*.jar"/>
        </classpath>
        <src>
            <pathelement path="Desktop/src"/>
            <pathelement path="src"/>
        </src>
    </javac>
</target>