package com.github.bjoernpetersen.jmusicbot.config;

import java.util.Optional;
import javax.annotation.Nonnull;

@FunctionalInterface
public interface ConfigChecker {

  @Nonnull
  Optional<String> check(@Nonnull String value);
}

@@ -61,21 +61,27 @@
 java
-.util.Optiona
+x.annotation.Nonnul
 l;%0Ai
@@ -104,22 +104,23 @@
 tation.N
-onn
 ull
+able
 ;%0A%0A@Func
@@ -175,35 +175,163 @@
 %0A%0A  
-@Nonnull%0A  Optional%3C
+/**%0A   * Checks whether the given value is valid.%0A   *%0A   * @param value a config value%0A   * @return an warning message, or null%0A   */%0A  @Nullable%0A  
 String
-%3E
  che

Modify ConfigChecker interface to return nullable String instead of optional