Allow lines to start with `@foo` inside a block tag like `{@code}`

IIRC, we currently consider such an appearance of `@foo` to be an invalid tag (or, if it is a recognized one like `@return`, maybe a valid tag? or maybe never a valid tag because we're upset that the previous inline tag was never closed?). It is invalid... until Java 15, at which point https://bugs.openjdk.org/browse/JDK-8241780 saves us.

On those grounds, we don't format the Javadoc at all (which is not necessarily a great failure mode, but that's another issue).

Maybe we should just allow this, at least for cases that are not normally Javadoc tags, like `@Override`?

Comece reproduzindo o caso de tag de bloco Javadoc descrito na issue, incluindo uma linha que comece com @Override, e use JDK-8241780 como contexto para o comportamento do Java 15. Nenhum arquivo ou teste é mencionado; deve-se considerar concluído quando o formatter aceitar as linhas @foo pretendidas sem tratar a tag inline ao redor como inválida.

Escrita pelo modelo de indexação a partir do texto da issue.