Add UseExplicitIsEmpty to AssertJ best practices

Author: timtebeek

src/main/resources/META-INF/rewrite/assertj.yml

@@ -25,6 +25,7 @@ recipeList:
   - org.openrewrite.java.testing.assertj.StaticImports
   - org.openrewrite.java.testing.assertj.JUnitToAssertj
   - org.openrewrite.java.testing.assertj.UseExplicitContains
+  - org.openrewrite.java.testing.assertj.UseExplicitIsEmpty
   - org.openrewrite.java.testing.assertj.UseExplicitSize
 
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