public void setDefaultEdgeColor(String themeColorId) {
		this.defaultEdgeColor = new GColor(themeColorId);
		defaultRegistrations.put(DEFAULT_EDGE_COLOR, themeColorId);
	}
Sets the default color to be used by vertices that don't have a vertex type set. The
color is set via a themeColorId, which means the client defined a theme color for this.
@param themeColorId the theme color id to use for the default vertex color
Ghidra/Framework/Graph/src/main/java/ghidra/service/graph/GraphDisplayOptions.java