Fixes #1509 [java] InvalidSlf4jMessageFormat NPE

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/logging/InvalidSlf4jMessageFormatRule.java

@@ -71,7 +71,15 @@ public class InvalidSlf4jMessageFormatRule extends AbstractJavaRule {
 		final List<ASTExpression> argumentList = parentNode.getFirstChildOfType(ASTPrimarySuffix.class)
 				.getFirstDescendantOfType(ASTArgumentList.class).findChildrenOfType(ASTExpression.class);
 		for (final ASTExpression astExpression : argumentList) {
-			params.add(astExpression.getFirstChildOfType(ASTPrimaryExpression.class));
+			ASTPrimaryExpression primaryExpression = astExpression.getFirstChildOfType(ASTPrimaryExpression.class);
+			if (primaryExpression != null) {
+			    params.add(primaryExpression);
+			}
+		}
+
+		if (params.isEmpty()) {
+		    // no params we could analyze
+		    return super.visit(node, data);
 		}
 
 		final ASTPrimaryExpression messageParam = params.get(0);

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/loggingjava/xml/InvalidSlf4jMessageFormat.xml

@@ -105,6 +105,26 @@ public class NullPointerTypeProblem {
             System.out.println(st.nextToken());
         }
     }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>#1509 [java] InvalidSlf4jMessageFormat NPE</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+package my.test;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class Test {
+
+    private static final Logger log = LoggerFactory.getLogger(Test.class);
+
+    public static void main(String[] args) {
+        log.info("1" + "2");
+    }
 }
         ]]></code>
     </test-code>

src/site/markdown/overview/changelog.md

@@ -12,4 +12,7 @@
 
 **Bugfixes:**
 
+*   java
+    *   [#1509](https://sourceforge.net/p/pmd/bugs/1509/) \[java] InvalidSlf4jMessageFormat NPE
+
 **API Changes:**