diff --git a/build/build.xml b/build/build.xml
index 76838973..fac195dc 100644
--- a/build/build.xml
+++ b/build/build.xml
@@ -1067,7 +1067,7 @@
 
 	<!-- checkcode.checkstyle ============================================================ -->
 	<target name="checkcode.checkstyle" description="Checkcode with checkstyle.">
-		<taskdef resource="checkstyletask.properties" classpath="build/lib/checkstyle.jar" />
+		<taskdef resource="com/puppycrawl/tools/checkstyle/ant/checkstyle-ant-task.properties" classpath="build/lib/checkstyle.jar"/>
 
 		<checkstyle maxErrors="17000" config="build/checkstyle.xml">
 			<fileset dir="src/java" includes="**/*.java" />
diff --git a/build/checkstyle.xml b/build/checkstyle.xml
index 8986c608..43ba0d4b 100644
--- a/build/checkstyle.xml
+++ b/build/checkstyle.xml
@@ -1,193 +1,210 @@
 <?xml version="1.0"?>
 <!DOCTYPE module PUBLIC
-          "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
-          "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
+        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
 
 <!--
+    Checkstyle configuration that checks the Google coding conventions from Google Java Style
+    that can be found at https://google.github.io/styleguide/javaguide.html.
 
-  Checkstyle configuration that checks the sun coding conventions from:
+    Checkstyle is very configurable. Be sure to read the documentation at
+    http://checkstyle.sf.net (or in your downloaded distribution).
 
-    - the Java Language Specification at
-      http://java.sun.com/docs/books/jls/second_edition/html/index.html
+    To completely disable a check, just comment it out or delete it from the file.
 
-    - the Sun Code Conventions at http://java.sun.com/docs/codeconv/
+    Authors: Max Vetrenko, Ruslan Diachenko, Roman Ivanov.
+ -->
 
-    - the Javadoc guidelines at
-      http://java.sun.com/j2se/javadoc/writingdoccomments/index.html
+<module name = "Checker">
+  <property name="charset" value="UTF-8"/>
 
-    - the JDK Api documentation http://java.sun.com/j2se/docs/api/index.html
+  <property name="severity" value="warning"/>
 
-    - some best practices
+  <property name="fileExtensions" value="java, properties, xml"/>
+  <!-- Checks for whitespace                               -->
+  <!-- See http://checkstyle.sf.net/config_whitespace.html -->
+  <module name="FileTabCharacter">
+    <property name="eachLine" value="true"/>
+  </module>
 
-  Checkstyle is very configurable. Be sure to read the documentation at
-  http://checkstyle.sf.net (or in your downloaded distribution).
-
-  Most Checks are configurable, be sure to consult the documentation.
-
-  To completely disable a check, just comment it out or delete it from the file.
-
-  Finally, it is worth reading the documentation.
-
--->
-
-<module name="Checker">
-    <!--
-        If you set the basedir property below, then all reported file
-        names will be relative to the specified directory. See
-        http://checkstyle.sourceforge.net/5.x/config.html#Checker
-
-        <property name="basedir" value="${basedir}"/>
-    -->
-
-    <!-- Checks that a package-info.java file exists for each package.     -->
-    <!-- See http://checkstyle.sf.net/config_javadoc.html#JavadocPackage -->
-    <module name="JavadocPackage"/>
-
-    <!-- Checks whether files end with a new line.                        -->
-    <!-- See http://checkstyle.sf.net/config_misc.html#NewlineAtEndOfFile -->
-    <module name="NewlineAtEndOfFile"/>
-
-    <!-- Checks that property files contain the same keys.         -->
-    <!-- See http://checkstyle.sf.net/config_misc.html#Translation -->
-    <module name="Translation"/>
-    
-    <!-- Checks for Size Violations.                    -->
-    <!-- See http://checkstyle.sf.net/config_sizes.html -->
-    <module name="FileLength"/>
-    
-    <!-- Checks for whitespace                               -->
-    <!-- See http://checkstyle.sf.net/config_whitespace.html -->
-    <module name="FileTabCharacter"/>
-
-    <!-- Miscellaneous other checks.                   -->
-    <!-- See http://checkstyle.sf.net/config_misc.html -->
-    <module name="RegexpSingleline">
-       <property name="format" value="\s+$"/>
-       <property name="minimum" value="0"/>
-       <property name="maximum" value="0"/>
-       <property name="message" value="Line has trailing spaces."/>
+  <module name="TreeWalker">
+    <module name="OuterTypeFilename"/>
+    <module name="IllegalTokenText">
+      <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
+      <property name="format" value="\\u00(08|09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
+      <property name="message" value="Avoid using corresponding octal or Unicode escape."/>
     </module>
-
-    <module name="TreeWalker">
-
-        <!-- Checks for Javadoc comments.                     -->
-        <!-- See http://checkstyle.sf.net/config_javadoc.html -->
-        <module name="JavadocMethod"/>
-        <module name="JavadocType"/>
-        <module name="JavadocStyle"/>
-
-
-        <!-- Checks for Naming Conventions.                  -->
-        <!-- See http://checkstyle.sf.net/config_naming.html -->
-        <module name="ConstantName"/>
-        <module name="LocalFinalVariableName"/>
-        <module name="LocalVariableName"/>
-        <module name="MemberName">
-         <property name="format" value="^_?[a-z][a-zA-Z0-9]*$"/>
-        </module>
-        <module name="MethodName"/>
-        <module name="PackageName"/>
-        <module name="ParameterName"/>
-        <module name="StaticVariableName"/>
-        <module name="TypeName"/>
-
-
-        <!-- Checks for Headers                                -->
-        <!-- See http://checkstyle.sf.net/config_header.html   -->
-        <!-- <module name="Header">                            -->
-            <!-- The follow property value demonstrates the ability     -->
-            <!-- to have access to ANT properties. In this case it uses -->
-            <!-- the ${basedir} property to allow Checkstyle to be run  -->
-            <!-- from any directory within a project. See property      -->
-            <!-- expansion,                                             -->
-            <!-- http://checkstyle.sf.net/config.html#properties        -->
-            <!-- <property                                              -->
-            <!--     name="headerFile"                                  -->
-            <!--     value="${basedir}/java.header"/>                   -->
-        <!-- </module> -->
-
-        <!-- Following interprets the header file as regular expressions. -->
-        <!-- <module name="RegexpHeader"/>                                -->
-
-
-        <!-- Checks for imports                              -->
-        <!-- See http://checkstyle.sf.net/config_import.html -->
-        <module name="AvoidStarImport"/>
-        <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
-        <module name="RedundantImport"/>
-        <module name="UnusedImports"/>
-
-
-        <!-- Checks for Size Violations.                    -->
-        <!-- See http://checkstyle.sf.net/config_sizes.html -->
-        <module name="LineLength">
-    	<property name="max" value="100"/>
-		</module>
-
-        
-        <module name="MethodLength"/>
-        <module name="ParameterNumber"/>
-
-
-        <!-- Checks for whitespace                               -->
-        <!-- See http://checkstyle.sf.net/config_whitespace.html -->
-        <module name="EmptyForIteratorPad"/>
-        <module name="GenericWhitespace"/>
-        <module name="MethodParamPad"/>
-        <module name="NoWhitespaceAfter"/>
-        <module name="NoWhitespaceBefore"/>
-        <module name="OperatorWrap"/>
-        <module name="ParenPad"/>
-        <module name="TypecastParenPad"/>
-        <module name="WhitespaceAfter"/>
-        <module name="WhitespaceAround"/>
-
-
-        <!-- Modifier Checks                                    -->
-        <!-- See http://checkstyle.sf.net/config_modifiers.html -->
-        <module name="ModifierOrder"/>
-        <module name="RedundantModifier"/>
-
-
-        <!-- Checks for blocks. You know, those {}'s         -->
-        <!-- See http://checkstyle.sf.net/config_blocks.html -->
-        <module name="AvoidNestedBlocks"/>
-        <module name="EmptyBlock"/>
-        <module name="LeftCurly"/>
-        <module name="NeedBraces"/>
-
-
-        <!-- Checks for common coding problems               -->
-        <!-- See http://checkstyle.sf.net/config_coding.html -->
-        <module name="AvoidInlineConditionals"/>
-        <module name="DoubleCheckedLocking"/>    <!-- MY FAVOURITE -->
-        <module name="EmptyStatement"/>
-        <module name="EqualsHashCode"/>
-        <module name="HiddenField"/>
-        <module name="IllegalInstantiation"/>
-        <module name="InnerAssignment"/>
-        <!-- <module name="MagicNumber"/> -->
-        <module name="MissingSwitchDefault"/>
-        <module name="RedundantThrows"/>
-        <module name="SimplifyBooleanExpression"/>
-        <module name="SimplifyBooleanReturn"/>
-
-        <!-- Checks for class design                         -->
-        <!-- See http://checkstyle.sf.net/config_design.html -->
-        <module name="DesignForExtension"/>
-        <module name="FinalClass"/>
-        <module name="HideUtilityClassConstructor"/>
-        <module name="InterfaceIsType"/>
-        <module name="VisibilityModifier"/>
-
-
-        <!-- Miscellaneous other checks.                   -->
-        <!-- See http://checkstyle.sf.net/config_misc.html -->
-        <module name="ArrayTypeStyle"/>
-        <module name="FinalParameters"/>
-        <module name="TodoComment"/>
-        <module name="UpperEll"/>
-
+    <module name="AvoidEscapedUnicodeCharacters">
+      <property name="allowEscapesForControlCharacters" value="true"/>
+      <property name="allowByTailComment" value="true"/>
+      <property name="allowNonPrintableEscapes" value="true"/>
     </module>
-
+    <module name="LineLength">
+      <property name="max" value="100"/>
+      <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
+    </module>
+    <module name="AvoidStarImport"/>
+    <module name="OneTopLevelClass"/>
+    <module name="NoLineWrap"/>
+    <module name="EmptyBlock">
+      <property name="option" value="TEXT"/>
+      <property name="tokens" value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
+    </module>
+    <module name="NeedBraces"/>
+    <module name="LeftCurly">
+      <property name="maxLineLength" value="100"/>
+    </module>
+    <module name="RightCurly"/>
+    <module name="RightCurly">
+      <property name="option" value="alone"/>
+      <property name="tokens" value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, LITERAL_DO, STATIC_INIT, INSTANCE_INIT"/>
+    </module>
+    <module name="WhitespaceAround">
+      <property name="allowEmptyConstructors" value="true"/>
+      <property name="allowEmptyMethods" value="true"/>
+      <property name="allowEmptyTypes" value="true"/>
+      <property name="allowEmptyLoops" value="true"/>
+      <message key="ws.notFollowed"
+               value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
+      <message key="ws.notPreceded"
+               value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
+    </module>
+    <module name="OneStatementPerLine"/>
+    <module name="MultipleVariableDeclarations"/>
+    <module name="ArrayTypeStyle"/>
+    <module name="MissingSwitchDefault"/>
+    <module name="FallThrough"/>
+    <module name="UpperEll"/>
+    <module name="ModifierOrder"/>
+    <module name="EmptyLineSeparator">
+      <property name="allowNoEmptyLineBetweenFields" value="true"/>
+    </module>
+    <module name="SeparatorWrap">
+      <property name="tokens" value="DOT"/>
+      <property name="option" value="nl"/>
+    </module>
+    <module name="SeparatorWrap">
+      <property name="tokens" value="COMMA"/>
+      <property name="option" value="EOL"/>
+    </module>
+    <module name="PackageName">
+      <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
+      <message key="name.invalidPattern"
+               value="Package name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="TypeName">
+      <message key="name.invalidPattern"
+               value="Type name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="MemberName">
+      <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
+      <message key="name.invalidPattern"
+               value="Member name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="ParameterName">
+      <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
+      <message key="name.invalidPattern"
+               value="Parameter name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="CatchParameterName">
+      <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
+      <message key="name.invalidPattern"
+               value="Catch parameter name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="LocalVariableName">
+      <property name="tokens" value="VARIABLE_DEF"/>
+      <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
+      <property name="allowOneCharVarInForLoop" value="true"/>
+      <message key="name.invalidPattern"
+               value="Local variable name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="ClassTypeParameterName">
+      <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
+      <message key="name.invalidPattern"
+               value="Class type name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="MethodTypeParameterName">
+      <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
+      <message key="name.invalidPattern"
+               value="Method type name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="InterfaceTypeParameterName">
+      <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
+      <message key="name.invalidPattern"
+               value="Interface type name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="NoFinalizer"/>
+    <module name="GenericWhitespace">
+      <message key="ws.followed"
+               value="GenericWhitespace ''{0}'' is followed by whitespace."/>
+      <message key="ws.preceded"
+               value="GenericWhitespace ''{0}'' is preceded with whitespace."/>
+      <message key="ws.illegalFollow"
+               value="GenericWhitespace ''{0}'' should followed by whitespace."/>
+      <message key="ws.notPreceded"
+               value="GenericWhitespace ''{0}'' is not preceded with whitespace."/>
+    </module>
+    <module name="Indentation">
+      <property name="basicOffset" value="2"/>
+      <property name="braceAdjustment" value="0"/>
+      <property name="caseIndent" value="2"/>
+      <property name="throwsIndent" value="4"/>
+      <property name="lineWrappingIndentation" value="4"/>
+      <property name="arrayInitIndent" value="2"/>
+    </module>
+    <module name="AbbreviationAsWordInName">
+      <property name="ignoreFinal" value="false"/>
+      <property name="allowedAbbreviationLength" value="1"/>
+    </module>
+    <module name="OverloadMethodsDeclarationOrder"/>
+    <module name="VariableDeclarationUsageDistance"/>
+    <module name="CustomImportOrder">
+      <property name="specialImportsRegExp" value="com.google"/>
+      <property name="sortImportsInGroupAlphabetically" value="true"/>
+      <property name="customImportOrderRules" value="STATIC###SPECIAL_IMPORTS###THIRD_PARTY_PACKAGE###STANDARD_JAVA_PACKAGE"/>
+    </module>
+    <module name="MethodParamPad"/>
+    <module name="OperatorWrap">
+      <property name="option" value="NL"/>
+      <property name="tokens" value="BAND, BOR, BSR, BXOR, DIV, EQUAL, GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR, LT, MINUS, MOD, NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR "/>
+    </module>
+    <module name="AnnotationLocation">
+      <property name="tokens" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
+    </module>
+    <module name="AnnotationLocation">
+      <property name="tokens" value="VARIABLE_DEF"/>
+      <property name="allowSamelineMultipleAnnotations" value="true"/>
+    </module>
+    <module name="NonEmptyAtclauseDescription"/>
+    <module name="JavadocTagContinuationIndentation"/>
+    <module name="SummaryJavadoc">
+      <property name="forbiddenSummaryFragments" value="^@return the *|^This method returns |^A [{]@code [a-zA-Z0-9]+[}]( is a )"/>
+    </module>
+    <module name="JavadocParagraph"/>
+    <module name="AtclauseOrder">
+      <property name="tagOrder" value="@param, @return, @throws, @deprecated"/>
+      <property name="target" value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
+    </module>
+    <module name="JavadocMethod">
+      <property name="scope" value="public"/>
+      <property name="allowMissingParamTags" value="true"/>
+      <property name="allowMissingThrowsTags" value="true"/>
+      <property name="allowMissingReturnTag" value="true"/>
+      <property name="minLineCount" value="2"/>
+      <property name="allowedAnnotations" value="Override, Test"/>
+      <property name="allowThrowsTagsForSubclasses" value="true"/>
+    </module>
+    <module name="MethodName">
+      <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9_]*$"/>
+      <message key="name.invalidPattern"
+               value="Method name ''{0}'' must match pattern ''{1}''."/>
+    </module>
+    <module name="SingleLineJavadoc">
+      <property name="ignoreInlineTags" value="false"/>
+    </module>
+    <module name="EmptyCatchBlock">
+      <property name="exceptionVariableName" value="expected"/>
+    </module>
+    <module name="CommentsIndentation"/>
+  </module>
 </module>
diff --git a/build/lib/checkstyle.jar b/build/lib/checkstyle.jar
old mode 100755
new mode 100644
index 2cc11b75..faeedde3
Binary files a/build/lib/checkstyle.jar and b/build/lib/checkstyle.jar differ
diff --git a/build/lib/versions.txt b/build/lib/versions.txt
index f33f8c94..53855e09 100644
--- a/build/lib/versions.txt
+++ b/build/lib/versions.txt
@@ -6,6 +6,7 @@ jarbundler-1.4.jar		 			| ?			 	 		| GPL				| http://informagen.com/JarBundler/i
 pack200task.jar			 			| ?			 	 		| Sun				| https://java-pack200-ant-task.dev.java.net/
 pmd.jar					 			| 4.2.5		 	 		| BSD				| http://pmd.sf.net
 asm.jar					 			| 3.1		 	 		| BSD				| http://pmd.sf.net
+checkstyle.jar                      | 6.18-all              | Apache 2          | https://sourceforge.net/projects/checkstyle/
 junit.jar							| 4.8.2					| CPL				| http://www.junit.org
 dist/activation.jar					| ? 			 		| Sun				| http://java.sun.com/javase/technologies/desktop/javabeans/jaf/downloads/index.html
 dist/asterisk-im-client.jar			| 2.0.0-SNAPSHOT        | GPL				| http://igniterealtime.org/