code: public Object resolveObject(String variable, int lineNumber, int startPosition) {
      if (StringUtils.isBlank(variable)) {
        return "";
      }
      if (WhitespaceUtils.isQuoted(variable)) {
        return WhitespaceUtils.unquote(variable);
      } else {
        Object val = retraceVariable(variable, lineNumber, startPosition);
        if (val == null) {
          return variable;
        }
        return val;
      }
    }
docs: Resolve a variable into an object value. If given a string literal (e.g. 'foo' or "foo"), this method returns the literal unquoted. If the variable is undefined in the context, this method returns the given variable string.
  
  @param variable
  name of variable in context
  @param lineNumber
  current line number, for error reporting
  @param startPosition
  current line position, for error reporting
  @return resolved value for variable