JSX boolean attribute "readOnly" should not use string values

[locomotif]

Q&A (please complete the following information)

• OS: macOS
• Browser: Chrome
• Version: 69.0.3497.100 (Official Build) (64-bit)
• Method of installation: yarn
• Swagger-UI version: 3.19.0
• Swagger/OpenAPI version: 3.19.0

To reproduce...

This is not necessarily a bug, but maybe a react best practice. When executing a sample rest endpoint, I am noticing a warning on the console. Please see screenshot below. The issue originates from swagger-ui/src/core/components/curl.jsx

Please note the readOnly attribute

<textarea onFocus={this.handleFocus} readOnly="true" className="curl" style={{ whiteSpace: "normal" }} value={curl}></textarea>
// ...should be
<textarea onFocus={this.handleFocus} readOnly className="curl" style={{ whiteSpace: "normal" }} value={curl}></textarea>

Expected behavior

I expect no warnings

Screenshots

[hkosova]

PR: #5497

[shockey]

fixed in #5497!