public static boolean parseOptionalBooleanAttr(Element ele, String attrName,
			boolean defaultValue) throws IOException {
		String value = ele.getAttributeValue(attrName);
		try {
			return (value != null) ? parseBoolean(value) : defaultValue;
		}
		catch (XmlAttributeException e) {
			throw new IOException("Attribute '" + attrName + "' bad boolean value: '" + value +
				"' in " + toString(ele));
		}
	}
Parses the optional attribute as a boolean value, returning its value or
the specified defaultValue if missing.

@param ele JDom element that contains the attribute
@param attrName the name of the xml attribute to parse
@param defaultValue boolean value to return if the attribute is not
           defined
@return boolean equiv of the attribute string value ("y", "true"/"n",
        "false")
@throws IOException if attribute value is not valid boolean string
Ghidra/Framework/Generic/src/main/java/ghidra/util/xml/XmlUtilities.java