guava/src/com/google/common/base/Optional.java
public static <T> @Nullable Optional<T> fromJavaUtil(
      java.util.@Nullable Optional<T> javaUtilOptional) {
    return (javaUtilOptional == null) ? null : fromNullable(javaUtilOptional.orElse(null));
  }
public static <T> @Nullable Optional<T> fromJavaUtil(
      java.util.@Nullable Optional<T> javaUtilOptional) {
    return (javaUtilOptional == null) ? null : fromNullable(javaUtilOptional.orElse(null));
  }
Returns the equivalent {@code com.google.common.base.Optional} value to the given {@code
java.util.Optional}, or {@code null} if the argument is null.

@since 21.0