private ResourceRequestEventImpl(final Builder builder) {
   this.resourceCount = BuilderUtils.notNull(builder.resourceCount);
   this.nodeNameList = BuilderUtils.notNull(builder.nodeNameList);
   this.rackNameList = BuilderUtils.notNull(builder.rackNameList);
   this.memorySize = Optional.ofNullable(builder.memorySize);
   this.priority = Optional.ofNullable(builder.priority);
   this.virtualCores = Optional.ofNullable(builder.virtualCores);
   this.relaxLocality = Optional.ofNullable(builder.relaxLocality);
 }
 private ResourceStatusEventImpl(final Builder builder) {
   this.identifier = BuilderUtils.notNull(builder.identifier);
   this.state = BuilderUtils.notNull(builder.state);
   this.diagnostics = Optional.ofNullable(builder.diagnostics);
   this.exitCode = Optional.ofNullable(builder.exitCode);
 }