driver-legacy/src/main/com/mongodb/DBCollection.java
public boolean isCapped() {
        CommandResult commandResult = getStats();
        Object cappedField = commandResult.get("capped");
        return cappedField != null && (cappedField.equals(1) || cappedField.equals(true));
    }
public boolean isCapped() {
        CommandResult commandResult = getStats();
        Object cappedField = commandResult.get("capped");
        return cappedField != null && (cappedField.equals(1) || cappedField.equals(true));
    }
Checks whether this collection is capped

@return true if this is a capped collection
@mongodb.driver.manual /core/capped-collections/#check-if-a-collection-is-capped Capped Collections