wffweb/src/main/java/com/webfirmframework/wffweb/tag/html/attribute/global/Style.java
public Collection<CssProperty> getCssProperties() {
        final long stamp = lock.readLock();
        try {
            return Collections.unmodifiableSet(cssProperties);
        } finally {
            lock.unlockRead(stamp);
        }
    }
public Collection<CssProperty> getCssProperties() {
        final long stamp = lock.readLock();
        try {
            return Collections.unmodifiableSet(cssProperties);
        } finally {
            lock.unlockRead(stamp);
        }
    }
gets the {@code Collection<CssProperty>}. It's unmodifiable set since
3.0.1.

@return {@code Collection<CssProperty>}
@since 1.0.0
@author WFF