@Override
  public org.springframework.shell.core.CommandResult executeCommand(String line) {
    return super.executeCommand(!line.contains("$") ? line : expandProperties(line));
  }
Executes a single command string.
It substitutes the variables defined within the command, if any, and then delegates to the
default execution.

@param line command string to be executed
@return command execution result.
geode-gfsh/src/main/java/org/apache/geode/management/internal/cli/shell/Gfsh.java