snaker-core/src/main/java/org/snaker/engine/handlers/impl/MergeBranchHandler.java
protected String[] findActiveNodes() {
		StringBuilder buffer = new StringBuilder(20);
		findForkTaskNames(model, buffer);
		String[] taskNames = buffer.toString().split(",");
		return taskNames;
	}
protected String[] findActiveNodes() {
		StringBuilder buffer = new StringBuilder(20);
		findForkTaskNames(model, buffer);
		String[] taskNames = buffer.toString().split(",");
		return taskNames;
	}
对join节点的所有输入变迁进行递归，查找join至fork节点的所有中间task元素
@see org.snaker.engine.handlers.impl.AbstractMergeHandler#findActiveNodes()