Public and protected members should be documented with Javadoc comments.
It is encouraged to document package-private and private members as well, especially if they are complex or not self-explanatory.
The first sentence of the Javadoc comment is the summary description. It should be a concise overview of what the method does and end with a period.
Use @param for method parameters. The description starts with a lowercase letter and does not end with a period.
Use @return for method return values.
Use @throws or @exception to document exceptions thrown by methods.
Use @see for references to other types or members.
Use {@inheritDoc} to inherit documentation from base classes or interfaces.
- Unless there is major behavior change, in which case you should document the differences.
Use @param <T> for type parameters in generic types or methods.
Use {@code} for inline code snippets.
Use <pre>{@code ... }</pre> for code blocks.
Use @since to indicate when the feature was introduced (e.g., version number).
Use @version to specify the version of the member.
Use @author to specify the author of the code.
Use @deprecated to mark a member as deprecated and provide an alternative.

java-docs

Java Documentation (Javadoc) Best Practices