#1633 [java] UnsynchronizedStaticFormatter reports commons lang FastDateFormat

Thread safe formatter org.apache.commons.lang3.time.FastDateFormat can not avoid UnsynchronizedStaticFormatterRule.

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/multithreading/UnsynchronizedStaticFormatterRule.java

@@ -5,6 +5,7 @@
 package net.sourceforge.pmd.lang.java.rule.multithreading;
 
 import java.text.Format;
+import java.util.Arrays;
 
 import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.lang.java.ast.ASTClassOrInterfaceType;
@@ -27,6 +28,9 @@ import net.sourceforge.pmd.lang.symboltable.NameOccurrence;
  */
 public class UnsynchronizedStaticFormatterRule extends AbstractJavaRule {
     private Class<?> formatterClassToCheck = Format.class;
+    private String[] threadSafeFormatter = {
+        "org.apache.commons.lang3.time.FastDateFormat",
+    };
 
     public UnsynchronizedStaticFormatterRule() {
         addRuleChainVisit(ASTFieldDeclaration.class);
@@ -48,6 +52,9 @@ public class UnsynchronizedStaticFormatterRule extends AbstractJavaRule {
         }
 
         ASTVariableDeclaratorId var = node.getFirstDescendantOfType(ASTVariableDeclaratorId.class);
+        if (Arrays.asList(threadSafeFormatter).contains(var.getType().getName())) {
+            return data;
+        }
         for (NameOccurrence occ : var.getUsages()) {
             Node n = occ.getLocation();
             if (n.getFirstParentOfType(ASTSynchronizedStatement.class) != null) {

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/multithreading/xml/UnsynchronizedStaticFormatter.xml

@@ -132,6 +132,20 @@ public class Foo {
     void bar() {
         messageFormat.format();
     }
+}
+     ]]></code>
+    </test-code>
+    <test-code>
+        <description>#1633 [java] UnsynchronizedStaticFormatter reports commons lang FastDateFormat</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+import org.apache.commons.lang3.time.FastDateFormat;
+
+public class Foo {
+    private static final FastDateFormat FDF = FastDateFormat.getInstance("dd.MM.yyyy HH:mm:ss");
+    public void format() {
+        FDF.format(new Date());
+    }
 }
      ]]></code>
     </test-code>