annotate via custom annotation

src/main/java/com/owncloud/android/ui/TextDrawable.java

@@ -30,6 +30,7 @@ import android.support.annotation.NonNull;
 
 import com.owncloud.android.authentication.AccountUtils;
 import com.owncloud.android.utils.BitmapUtils;
+import com.owncloud.android.utils.NextcloudServer;
 
 import java.io.UnsupportedEncodingException;
 import java.security.NoSuchAlgorithmException;
@@ -95,6 +96,7 @@ public class TextDrawable extends Drawable {
      * @throws NoSuchAlgorithmException     if the specified algorithm is not available when calculating the color values
      */
     @NonNull
+    @NextcloudServer(min = -1, max = 12)
     public static TextDrawable createAvatar(String accountName, float radiusInDp) throws
             UnsupportedEncodingException, NoSuchAlgorithmException {
         String username = AccountUtils.getAccountUsername(accountName);

src/main/java/com/owncloud/android/utils/NextcloudServer.java

@@ -0,0 +1,18 @@
+package com.owncloud.android.utils;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Created by tobi on 21.12.17.
+ */
+
+@Retention(RetentionPolicy.SOURCE)
+@Target(ElementType.METHOD)
+public @interface NextcloudServer {
+    int min();
+
+    int max();
+}