assertNull(options.getDestinationDirectory());
        assertFalse(options.isUse());
        assertFalse(options.isVersion());
        assertFalse(options.isAuthor());
        assertFalse(options.isSplitIndex());
        assertNull(options.getWindowTitle());
        assertNull(options.getDocTitle());
        assertNull(options.getFooter());
        assertNull(options.getBottom());
        assertEmpty(options.getLinks());

     * Splits the index file into multiple files, alphabetically, one file per letter,
     * plus a file for any index entries that start with non-alphabetical characters.
     */
    @Input
    public boolean isSplitIndex() {
        return splitIndex.getValue();
    }

    public void setSplitIndex(boolean splitIndex) {
        this.splitIndex.setValue(splitIndex);
    }

Method <org.gradle.external.javadoc.StandardJavadocDocletOptions.isSplitIndex()> does not have raw return type assignable to org.gradle.api.provider.Property in (StandardJavadocDocletOptions.java:0)