src/main/java/org/valid4j/matchers/ArgumentMatchers.java
@Factory
  public static Matcher<String> notEmptyString() {
    return new CustomTypeSafeMatcher<String>("not empty") {
      @Override
      protected boolean matchesSafely(String s) {
        return !s.isEmpty();
      }
    };
  }
@Factory
  public static Matcher<String> notEmptyString() {
    return new CustomTypeSafeMatcher<String>("not empty") {
      @Override
      protected boolean matchesSafely(String s) {
        return !s.isEmpty();
      }
    };
  }
A matcher matching non-null and non-empty strings

Example:
<pre>assertThat("this is not an empty string", notEmptyString())</pre>

@return
matcher for a not empty string