public void checkReadOnly() {
    if (isReadOnly()) {
      throw new IllegalStateException(
          "This configuration cannot be modified while its managed entity is running.");
    }
  }
Checks to see if this config object is "read only". If it is, then an
{@link IllegalStateException} is thrown. It should be called by every setter method.

@see #isReadOnly
geode-core/src/main/java/org/apache/geode/admin/internal/ManagedEntityConfigImpl.java