在下面的xml中，我收到dtd标记中的错误。为什么会出现以下错误？是否缺少文件？
引用文件包含错误（http://users.tpg.com.au/ojburn/dtds/configuration_1_3.dtd）。
Xml 1：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.3//EN" "http://users.tpg.com.au/ojburn/dtds/configuration_1_3.dtd">
<!--
This configuration file was written by the eclipse-cs plugin configuration editor
-->
<!--
Checkstyle-Configuration: gwtp
Description: none
-->
<module name="Checker">
<property name="severity" value="warning"/>
<module name="TreeWalker">
<property name="cacheFile" value="${basedir}/${cache.file}"/>
<module name="LineLength">
<property name="max" value="150"/>
</module>
<module name="FileContentsHolder"/>
<module name="UnnecessaryParentheses"/>
<module name="ExplicitInitialization"/>
<module name="ParameterAssignment"/>
<module name="JUnitTestCase"/>
<module name="StringLiteralEquality"/>
<module name="SimplifyBooleanReturn"/>
<module name="SimplifyBooleanExpression"/>
<module name="ModifiedControlVariable"/>
<module name="MissingSwitchDefault"/>
<module name="MissingOverride"/>
<module name="InterfaceIsType"/>
<module name="RedundantImport"/>
<module name="UnusedImports"/>
<module name="ParameterName"/>
<module name="LocalFinalVariableName"/>
<module name="LocalVariableName">
<property name="tokens" value="PARAMETER_DEF,VARIABLE_DEF"/>
</module>
<module name="LeftCurly"/>
<module name="RightCurly"/>
<module name="CovariantEquals"/>
<module name="HiddenField">
<property name="tokens" value="VARIABLE_DEF"/>
<property name="ignoreConstructorParameter" value="true"/>
<property name="ignoreSetter" value="true"/>
</module>
<module name="IllegalInstantiation">
<property name="classes" value="java.lang.Boolean"/>
</module>
<module name="UpperEll">
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="checking for 4l rather than 4L"/>
</module>
<module name="JavadocStyle">
<property name="severity" value="info"/>
<property name="checkHtml" value="false"/>
<property name="tokens" value="CLASS_DEF,CTOR_DEF,INTERFACE_DEF,METHOD_DEF,VARIABLE_DEF"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="Well formed java docs"/>
</module>
<module name="NeedBraces">
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="make sure if has braces"/>
</module>
<module name="JavadocMethod">
<property name="severity" value="info"/>
<property name="scope" value="protected"/>
<property name="allowUndeclaredRTE" value="true"/>
<property name="allowMissingParamTags" value="true"/>
<property name="allowMissingThrowsTags" value="true"/>
<property name="allowMissingReturnTag" value="true"/>
<property name="allowMissingJavadoc" value="true"/>
<property name="allowMissingPropertyJavadoc" value="true"/>
<property name="logLoadErrors" value="true"/>
<property name="tokens" value="METHOD_DEF"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.lastEnabledSeverity" value="info"/>
</module>
<module name="DefaultComesLast"/>
<module name="MultipleStringLiterals">
<property name="severity" value="info"/>
<property name="ignoreStringsRegexp" value=".{0,3}"/>
</module>
<module name="FallThrough"/>
<module name="IllegalInstantiation">
<property name="classes" value="Boolean"/>
</module>
<module name="Regexp">
<property name="severity" value="info"/>
<property name="format" value="[^:^"]:" .*+"/>
<property name="message" value="check that a space is left after a colon on an assembled error message"/>
<property name="illegalPattern" value="true"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="check that a space is left after a colon with an assembled error message"/>
</module>
<module name="Regexp">
<property name="severity" value="info"/>
<property name="format" value="[\r]?[\n][ \t]*[\r]?[\n][ \t]*[\r]?[\n][ \t]*"/>
<property name="message" value="more than one blank line"/>
<property name="illegalPattern" value="true"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="more than one blank line"/>
</module>
<module name="WhitespaceAround">
<property name="tokens" value="COLON,NOT_EQUAL,QUESTION,DIV,DIV_ASSIGN,BXOR,BXOR_ASSIGN,MINUS,LCURLY,STAR,STAR_ASSIGN,TYPE_EXTENSION_AND,BAND,LAND,BAND_ASSIGN,MOD,MOD_ASSIGN,PLUS,PLUS_ASSIGN,LT,SL,SL_ASSIGN,LE,ASSIGN,MINUS_ASSIGN,EQUAL,GT,GE,SR,SR_ASSIGN,BSR,BSR_ASSIGN,BOR,BOR_ASSIGN,LOR,LITERAL_ASSERT,LITERAL_ASSERT,LITERAL_CATCH,LITERAL_DO,LITERAL_ELSE,LITERAL_FINALLY,LITERAL_FOR,LITERAL_IF,LITERAL_RETURN,SLIST,LITERAL_SYNCHRONIZED,LITERAL_TRY,LITERAL_WHILE"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="Must have spaces"/>
</module>
<module name="Regexp">
<property name="format" value="[\r]?[\n][ \t]*[\r]?[\n][ \t]+[}][ ]*[\n]"/>
<property name="message" value="newline before }"/>
<property name="illegalPattern" value="true"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="newline before }"/>
</module>
<module name="ModifierOrder"/>
<module name="AvoidStarImport"/>
<module name="EmptyStatement"/>
<module name="MethodName"/>
<module name="MemberName">
<property name="format" value="[a-z]|[a-z][a-z_0-9][A-Za-z0-9_]*|[a-z](?<!f)[A-Z0-9]*"/>
</module>
<module name="Regexp">
<property name="format" value="[/][*][*][^\n]*[*][/]"/>
<property name="message" value="No one line javadoc comments"/>
<property name="illegalPattern" value="true"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="No one line javadoc comments"/>
</module>
<module name="NoWhitespaceAfter">
<property name="allowLineBreaks" value="false"/>
<property name="tokens" value="BNOT,DEC,DOT,INC,LNOT,UNARY_MINUS,UNARY_PLUS"/>
</module>
<module name="WhitespaceAfter">
<property name="tokens" value="TYPECAST"/>
</module>
<module name="TypecastParenPad">
<property name="tokens" value="RPAREN,TYPECAST"/>
</module>
<module name="ParenPad"/>
<module name="MethodParamPad"/>
<module name="NoWhitespaceBefore"/>
<module name="NoWhitespaceBefore">
<property name="allowLineBreaks" value="true"/>
<property name="tokens" value="DOT"/>
</module>
<module name="RedundantModifier"/>
<module name="EqualsHashCode"/>
</module>
<module name="JavadocPackage">
<property name="severity" value="ignore"/>
<metadata name="net.sf.eclipsecs.core.lastEnabledSeverity" value="inherit"/>
</module>
<module name="FileTabCharacter">
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="no tabs"/>
</module>
<module name="RegexpSingleline">
<property name="format" value=" [/][/][A-z]"/>
<property name="message" value="// comments must be followed by a space and be on their own line"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="bad // comment"/>
</module>
<module name="SuppressionCommentFilter">
<property name="offCommentFormat" value="CHECKSTYLE_OFF"/>
<property name="onCommentFormat" value="CHECKSTYLE_ON"/>
</module>
<module name="SuppressionCommentFilter">
<property name="offCommentFormat" value="CHECKSTYLE_NAMING_OFF"/>
<property name="onCommentFormat" value="CHECKSTYLE_NAMING_ON"/>
<property name="checkFormat" value=".*Name.*"/>
<property name="messageFormat" value=".*name.*"/>
<metadata name="com.atlassw.tools.eclipse.checkstyle.comment" value="Avoid name checking"/>
</module>
<module name="RegexpSingleline">
<!-- Check trailing spaces for all lines exept empty javadoc lines, due to eclipse formatter issue. See https://bugs.eclipse.org/bugs/show_bug.cgi?id=360523 -->
<property name="format" value="^((?!\s*\*).*)\s+$"/>
<property name="message" value="Line has trailing spaces."/>
</module>
<!-- <module name="Header">
<property name="fileExtensions" value="java"/>
<property name="headerFile" value="${basedir}/${header.file}"/>
</module> -->
<module name="SuppressionFilter">
<property name="file" value="${basedir}/${suppressions.file}"/>
</module>
</module>
Xml 2：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suppressions PUBLIC
"-//Puppy Crawl//DTD Suppressions 1.1//EN"
"http://users.tpg.com.au/ojburn/dtds/suppressions_1_1.dtd">
<suppressions>
<!-- Suppress MagicNumberCheck for files under test -->
<suppress checks="MagicNumberCheck" files=".*[/\\]test[/\\].*" />
<!-- Suppress MagicNumberCheck for files under test -->
<suppress checks="JavadocType" files=".*[/\\]test[/\\].*" />
<!-- Suppress files under target -->
<suppress checks=".*" files=".*[/\\]target[/\\].*" />
<!-- Suppress files under com/google -->
<suppress checks=".*" files="com[/\\]google[/\\]" />
<!-- Suppress variable name check for ApplicationErrorGeneratorInterface -->
<suppress checks="MethodNameCheck" files=".*ApplicationErrorGeneratorInterface.java" />
</suppressions>