It throws the exception below. I think maybe the initial value should be quoted to be a string value, eg:
    @Styleable(property="-fx-echo-char", initial="\"*\"")


java.lang.NullPointerException
at com.sun.javafx.css.parser.CSSParser.valueFor(CSSParser.java:461)
at com.sun.javafx.css.parser.CSSParser.parseExpr(CSSParser.java:171)
at com.sun.javafx.css.StyleableProperty.parse(StyleableProperty.java:660)
at com.sun.javafx.css.StyleableProperty.getInitialValue(StyleableProperty.java:222)
at com.javafx.experiments.artifex.cssdataextractor.StyleableExtractor.getCssSettableProperties(StyleableExtractor.java:82)
at com.javafx.experiments.artifex.cssdataextractor.ComponentTreeBuilder.createControlModelFromNode(ComponentTreeBuilder.java:135)
at com.javafx.experiments.artifex.cssdataextractor.ComponentTreeBuilder.extractCssInfo(ComponentTreeBuilder.java:92)
at com.javafx.experiments.artifex.cssdataextractor.ComponentTreeBuilder.extractCssInfo(ComponentTreeBuilder.java:79)
at com.javafx.experiments.artifex.cssdataextractor.Extractor$2.run(Extractor.java:73)
at com.sun.javafx.application.PlatformImpl$2.run(PlatformImpl.java:65)