Need accordion mode to prevent collapsing all sections

[rickthepick]

Currently in accordion mode (accordion=true) all the sections can be collapsed. We need a flag so that there is always one section open, e.g., if a section is open you cannot click on that section to collapse it.

[ghost]

I solved this by utilizing the onChange callback and state.

Example with React 16.8:

const Accordion = () => {
  const [activeKey, setActiveKey] = React.useState(`0`)

  return (
    <Collapse
      accordion={true}
      activeKey={activeKey}
      onChange={key => {
        setActiveKey(key || activeKey)
      }}
    >
      ...
    </Collapse>
  )
}

But a convenient flag would be much appreciated!