private boolean childGroupAdded(ProgramNode node, Group group) {

		int nchild = node.getChildCount();
		for (int i = 0; i < nchild; i++) {
			ProgramNode child = (ProgramNode) node.getChildAt(i);

			if (group.equals(child.getGroup())) {
				return true;
			}
		}
		return false;
	}
Return true if the node already has a child node with
the given group.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/programtree/ProgramDnDTree.java