You are actually pretty close, just keep the brackets. I just separated things a bit.
final WebElement mapLockElement = browser.findElement(By.className("mapLock")); final WebElement mapLockDisplayElement = mapLockElement.findElement("mapLockDisplay"); mapLockDisplayElement.click();
If you do it all on one line, it will be
browser.findElement(By.className("mapLock")).findElement(By.className("mapLockDisplay")).click();
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