/// <param name="symbolPart">Specific part of the symbol to which the attributes apply, or <see cref="AttributeLocation.None"/> if the attributes apply to the symbol itself.</param>
/// <param name="earlyDecodingOnly">Indicates that only early decoding should be performed. WARNING: the resulting bag will not be sealed.</param>
/// <param name="addToDiagnostics">Diagnostic bag to report into. If null, diagnostics will be reported into <see cref="AddDeclarationDiagnostics"/></param>
/// <returns>Flag indicating whether lazyCustomAttributes were stored on this thread. Caller should check for this flag and perform NotePartComplete if true.</returns>