code: private String absolutifyFilePath(final String path, final String referencePath) {
          // can't handle EL-expressions
          if (isElExpression(path)) {
              return path;
          }
  
          String normalizedPath;
          if (!path.startsWith("/")) {
              Path reference = Paths.get(referencePath);
              normalizedPath = reference.getParent().resolve(path).normalize().toString();
          } else {
              normalizedPath = Paths.get(path).normalize().toString();
          }
  
          return normalizeFilePath(normalizedPath);
      }
docs: <p>
  Try to make an absolute path from a relative path and a reference path.
  </p>
  
  <p>
  <b>Example:</b><br>
  <i>path</i> - ../../a/b.jspx<br>
  <i>referencePath</i> - c/d/e/f.jspx<br>
  <b>Result: c/a/b.jspx</b>
  </p>
  
  @param path
  the relative path
  @param referencePath
  the reference file path (should be absolute)
  
  @return a path absolute path in reference to the second path.