public void muteToType(LeafType newType) {
		checkNotGroup();
		if (newType == null) {
			throw new IllegalArgumentException();
		}
		if (leafType != LeafType.ABSTRACT_CLASS && leafType != LeafType.CLASS && leafType != LeafType.ENUM
				&& leafType != LeafType.INTERFACE) {
			throw new IllegalArgumentException("type=" + leafType);
		}
		if (newType != LeafType.ABSTRACT_CLASS && newType != LeafType.CLASS && newType != LeafType.ENUM
				&& newType != LeafType.INTERFACE) {
			throw new IllegalArgumentException("newtype=" + newType);
		}
		this.leafType = newType;
	}