code: public void setRelativePath(QPath relPath) {
          if (relPath != null && relPath.isAbsolute()) {
              throw new IllegalArgumentException("relPath must be relative");
          }
          this.relPath = relPath;
          if (relPath == null) {
              // context node is never a property
              propertyRef = false;
          }
      }
docs: Sets the relative path to the item where the textsearch is performed. If
  <code>relPath</code> is <code>null</code> the textsearch is performed on
  the context node.
  
  @param relPath the relative path to an item.
  @throws IllegalArgumentException if <code>relPath</code> is absolute.