make sure target dir exists

Author: hauner

src/main/java/io/openapiprocessor/maven/ProcessMojo.java

@@ -72,6 +72,7 @@ public void execute () throws MojoExecutionException {
             log.info(String.format ("%10s - %s", "targetDir", joinDirs("${project.basedir}", relativeTargetDir)));
 
             File targetRoot = new File(targetDir);
+            makeDirs(targetRoot);
             UpToDateCheck upToDateCheck = new UpToDateCheck ();
             boolean upToDate = upToDateCheck.isUpToDate (source.getParentFile(), targetRoot);
 
@@ -97,6 +98,11 @@ private String getProcessor () {
         return id;
     }
 
+    @SuppressWarnings("ResultOfMethodCallIgnored")
+    private void makeDirs(File dir) {
+        dir.mkdirs();
+    }
+
     private String stripBaseDir (String source) {
         Path base = Paths.get (project.getBasedir().getAbsolutePath ());
         Path src = Paths.get (source);