@@ -26,7 +26,9 @@ import java.io.IOException;
 import java.util.Objects;
 
 public class OverseerSolrResponse extends SolrResponse {
-  
+ 
+  private static final long serialVersionUID = 4721653044098960880L;
+
   NamedList<Object> responseList = null;
 
   private long elapsedTime;
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.solr.cloud;

import org.apache.solr.client.solrj.SolrResponse;
import org.apache.solr.common.SolrException;
import org.apache.solr.common.SolrException.ErrorCode;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.common.util.Utils;

import java.io.IOException;
import java.util.Objects;

public class OverseerSolrResponse extends SolrResponse {
  
  NamedList<Object> responseList = null;

  private long elapsedTime;
  
  public OverseerSolrResponse(NamedList list) {
    responseList = list;
  }
  
  @Override
  public long getElapsedTime() {
    return elapsedTime;
  }
  
  @Override
  public void setResponse(NamedList<Object> rsp) {
    this.responseList = rsp;
  }

  @Override
  public void setElapsedTime(long elapsedTime) {
    this.elapsedTime = elapsedTime;
  }

  @Override
  public NamedList<Object> getResponse() {
    return responseList;
  }

  /**
   * This method serializes the content of an {@code OverseerSolrResponse}. Note that:
   * <ul>
   * <li>The elapsed time is not serialized</li>
   * <li>"Unknown" elements for the Javabin format will be serialized as Strings. See {@link org.apache.solr.common.util.JavaBinCodec#writeVal}</li>
   * </ul>
   */
  @SuppressWarnings("deprecation")
  public static byte[] serialize(OverseerSolrResponse responseObject) {
    Objects.requireNonNull(responseObject);
    if (useUnsafeSerialization()) {
      return SolrResponse.serializable(responseObject);
    }
    try {
      return Utils.toJavabin(responseObject.getResponse()).readAllBytes();
    } catch (IOException|RuntimeException e) {
      throw new SolrException(ErrorCode.SERVER_ERROR, "Exception serializing response to Javabin", e);
    }
  }
  
  static boolean useUnsafeSerialization() {
    String useUnsafeOverseerResponse = System.getProperty("solr.useUnsafeOverseerResponse");
    return useUnsafeOverseerResponse != null && ("true".equals(useUnsafeOverseerResponse));
  }
  
  static boolean useUnsafeDeserialization() {
    String useUnsafeOverseerResponse = System.getProperty("solr.useUnsafeOverseerResponse");
    return useUnsafeOverseerResponse != null && ("true".equals(useUnsafeOverseerResponse) || "deserialization".equals(useUnsafeOverseerResponse));
  }

  @SuppressWarnings("deprecation")
  public static OverseerSolrResponse deserialize(byte[] responseBytes) {
    Objects.requireNonNull(responseBytes);
    try {
      @SuppressWarnings("unchecked")
      NamedList<Object> response = (NamedList<Object>) Utils.fromJavabin(responseBytes);
      return new OverseerSolrResponse(response);
    } catch (IOException|RuntimeException e) {
      if (useUnsafeDeserialization()) {
        return (OverseerSolrResponse) SolrResponse.deserialize(responseBytes);
      }
      throw new SolrException(ErrorCode.SERVER_ERROR, "Exception deserializing response from Javabin", e);
    }
  }
  
}

My understanding is that this number can actually vary depending on the compiler, so setting it to a specific value like this (expecting it to be number the class had in previous versions) may not work for everyone. Since the changes done in SOLR-14095 are just addition of static methods, maybe the better solution is to just revert them from OverseerSolrResponse and put them in some other util class