diff --git a/src/main/java/org/sonar/plugins/findbugs/FindbugsConfiguration.java b/src/main/java/org/sonar/plugins/findbugs/FindbugsConfiguration.java
index 247b8815..0ae3e2ce 100644
--- a/src/main/java/org/sonar/plugins/findbugs/FindbugsConfiguration.java
+++ b/src/main/java/org/sonar/plugins/findbugs/FindbugsConfiguration.java
@@ -207,7 +207,7 @@ File saveIncludeConfigXml() throws IOException {
    * Scan the given folder for classes. It will catch classes from Java, JSP and more.
    *
    * @param folder Folder to scan
-   * @return
+   * @return List<File> of class files
    * @throws IOException
    */
   public static List<File> scanForAdditionalClasses(File folder) throws IOException {
diff --git a/src/main/java/org/sonar/plugins/findbugs/FindbugsSensor.java b/src/main/java/org/sonar/plugins/findbugs/FindbugsSensor.java
index fa59f555..3749eaf8 100644
--- a/src/main/java/org/sonar/plugins/findbugs/FindbugsSensor.java
+++ b/src/main/java/org/sonar/plugins/findbugs/FindbugsSensor.java
@@ -197,9 +197,11 @@ public void execute(SensorContext context) {
       }
 
     }
-      finally {
-      classMappingWriter.flush();
-      classMappingWriter.close();
+    finally {
+      if(classMappingWriter != null) {
+        classMappingWriter.flush();
+        classMappingWriter.close();
+      }
     }
   }
 
diff --git a/src/main/java/org/sonar/plugins/findbugs/resource/ByteCodeResourceLocator.java b/src/main/java/org/sonar/plugins/findbugs/resource/ByteCodeResourceLocator.java
index 21a8d597..1a33bb8e 100644
--- a/src/main/java/org/sonar/plugins/findbugs/resource/ByteCodeResourceLocator.java
+++ b/src/main/java/org/sonar/plugins/findbugs/resource/ByteCodeResourceLocator.java
@@ -54,7 +54,7 @@ public class ByteCodeResourceLocator {
      * findSourceFileKeyByClassName() is broken in SonarQube 6.3.1.. This method is fixing it.
      * @param className
      * @param javaResourceLocator
-     * @return
+     * @return String filepath
      */
     public String findSourceFileKeyByClassName(String className, JavaResourceLocator javaResourceLocator) {
         InputFile input = javaResourceLocator.findResourceByClassName(className);
diff --git a/src/main/java/org/sonar/plugins/findbugs/resource/JasperUtils.java b/src/main/java/org/sonar/plugins/findbugs/resource/JasperUtils.java
index 5687a4b0..05938a87 100644
--- a/src/main/java/org/sonar/plugins/findbugs/resource/JasperUtils.java
+++ b/src/main/java/org/sonar/plugins/findbugs/resource/JasperUtils.java
@@ -43,7 +43,7 @@ public static final String mangleChar(char ch)
   /**
    * Detect if the character is printable
    * @param c Character to test
-   * @return
+   * @return boolean true if its a printable char otherwise false
    */
   public static boolean isPrintableChar( char c ) {
     Character.UnicodeBlock block = Character.UnicodeBlock.of( c );