This comment starts with /**, but isn't actually Javadoc.

Javadoc comments must precede a class, field, constructor, or method declaration.

Using /** comments in locations where Javadoc is not supported is confusing and unnecessary.

Suggested solutions:

NOTE: Javadoc must appear before any annotations, or the compiler will fail to recognise it as Javadoc. That is, prefer this:

/** Might return a frobnicator. */
@Nullable
Frobnicator getFrobnicator();

instead of this:

@Nullable
/** Might return a frobnicator. */
Frobnicator getFrobnicator();

Suppression

Suppress by applying @SuppressWarnings("NotJavadoc") to the enclosing element.