added AvoidSimpleDateFormat for Kotlin

src/main/resources/category/kotlin/common.xml

@@ -133,4 +133,47 @@ class Foo {
         </example>
     </rule>
 
+    <rule name="AvoidSimpleDateFormat"
+          class="net.sourceforge.pmd.lang.rule.XPathRule"
+          dfa="false"
+          language="kotlin"
+          message="SimpleDateFormat is used. Since it is thread-unsafe, it needs expensive recreation."
+          typeResolution="true"
+          externalInfoUrl="${doc_root}/JavaCodePerformance.md#idtf01">
+        <description>Problem: java.util.SimpleDateFormat is thread-unsafe. The usual solution is to create a new one when needed in a method. Creating SimpleDateFormat is relatively expensive. &#13;
+            Solution: Use java.time.DateTimeFormatter. These classes are immutable, thus thread-safe and can be made static.
+            (jpinpoint-rules)</description>
+        <priority>2</priority>
+        <properties>
+            <property name="tag" value="jpinpoint-rule" type="String" description="for-sonar"/>
+            <property name="version" value="3.1"/>
+            <property name="xpath">
+                <value><![CDATA[
+(: check if java.text imports exists as filter for same named classes in other packages :)
+//ImportHeader[.//T-Identifier[@Text='java'] and .//T-Identifier[@Text='text']][1]/../..
+
+(: if used in setDateFormat function, allow if jackson ObjectMapper or XmlMapper is used :)
+//ClassMemberDeclaration//SimpleIdentifier//T-Identifier[(@Text="SimpleDateFormat")
+  and not (ancestor::ClassMemberDeclaration//T-Identifier[@Text="setDateFormat"]
+              and //ImportHeader[.//T-Identifier[@Text='fasterxml'] and .//T-Identifier[@Text='jackson']]
+          )
+]
+                ]]></value>
+            </property>
+        </properties>
+        <example><![CDATA[
+import java.text.SimpleDateFormat
+import java.util.*
+
+class Foo {
+    private fun toKey(calcDate: Date): String {
+        val formatter = SimpleDateFormat("yyyy-MM-dd") //bad
+        return formatter.format(calcDate)
+    }
+}
+]]>
+        </example>
+    </rule>
+
+
 </ruleset>

src/test/java/com/jpinpoint/perf/lang/kotlin/ruleset/common/AvoidSimpleDateFormatTest.java

@@ -0,0 +1,6 @@
+package com.jpinpoint.perf.lang.kotlin.ruleset.common;
+
+import net.sourceforge.pmd.testframework.PmdRuleTst;
+
+public class AvoidSimpleDateFormatTest extends PmdRuleTst {
+}

src/test/resources/com/jpinpoint/perf/lang/kotlin/ruleset/common/xml/AvoidSimpleDateFormat.xml

@@ -0,0 +1,68 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<test-data
+        xmlns="http://pmd.sourceforge.net/rule-tests"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="http://pmd.sourceforge.net/rule-tests http://pmd.sourceforge.net/rule-tests_1_0_0.xsd">
+    <test-code>
+        <description>violation: Avoid the use of SimpleDateFormat</description>
+        <expected-problems>1</expected-problems>
+        <expected-linenumbers>6</expected-linenumbers>
+        <code><![CDATA[
+import java.text.SimpleDateFormat
+import java.util.*
+
+class Foo {
+    private fun toKey(rekenDatum: Date): String {
+        val formatter = SimpleDateFormat("yyyy-MM-dd") //bad
+        return formatter.format(rekenDatum)
+    }
+}
+     ]]></code>
+    </test-code>
+    <test-code>
+        <description>no violation: SimpleDateFormat is allowed in Jackon's ObjectMapper</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.dataformat.xml.XmlMapper
+import java.text.SimpleDateFormat
+
+object Foo {
+    private val OBJECT_MAPPER = createObjectMapper()
+    private val XML_MAPPER: XmlMapper
+    private val unknown: Unknown = createUnknownObject()
+
+    init {
+        XML_MAPPER = XmlMapper()
+        val df = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss") // good, used in XmlMapper
+        XML_MAPPER.setDateFormat(df)
+    }
+
+    private fun createObjectMapper(): ObjectMapper {
+        val mapper = ObjectMapper()
+        mapper.setDateFormat(SimpleDateFormat("yyyy-MM-dd")) // good, used in ObjectMapper
+        return mapper
+    }
+
+}
+        ]]></code>
+    </test-code>
+    <test-code>
+        <description>violation: SimpleDateFormat is not allowed in non XmlMapper or ObjectMapper</description>
+        <expected-problems>1</expected-problems>
+        <expected-linenumbers>8</expected-linenumbers>
+        <code><![CDATA[
+import java.text.SimpleDateFormat
+
+object Foo {
+    private val unknown: Unknown = createUnknownObject()
+
+    private fun createUnknownObject(): Unknown {
+        val unknown: Unknown = Unknown()
+        unknown.setDateFormat(SimpleDateFormat("yyyy-MM-dd")) // bad, used in unknown object
+        return unknown
+    }
+}
+        ]]></code>
+    </test-code>
+</test-data>