@Nullable
    public static String getProjectBuildDirectory(@Nonnull Element projectElt) {
        Element build = XmlUtils.getUniqueChildElementOrNull(projectElt, "build");
        if (build == null) {
            return null;
        }
        return build.getAttribute("directory");
    }
@ Nullable public static String getProjectBuildDirectory ( @ Nonnull Element projectElt ) { Element build = XmlUtils . getUniqueChildElementOrNull ( projectElt , "build" ) ; if ( build == null ) { return null ; } return build . getAttribute ( "directory" ) ; }
@param projectElt
@return {@code project/build/@directory"}