title: Corda: error=org.hibernate.InstantiationException: No default constructor for entity
body: <p>I met a issue, please to help. Corda Code based on M13. My Schema code this is mainly use define a schema refer your sample.</p>
  
  <pre><code>object LegalContractSchemaV1 : MappedSchema(
          schemaFamily = LegalContractSchema.javaClass,
          version = 1,
          mappedTypes = listOf(PersistentLegalContractState::class.java)) {
  
      @Entity
      @Table(name = "legal_contract_states")
         class PersistentLegalContractState(
              @Column(name = "contract_title`enter code here`")
              var contractTitle: String,
  
              @Column(name = "sender_name")
              var senderName: String,
  
              @Column(name = "recipient_name")
              var recipientName: String,
  
              @Column(name = "status")
              var status: String) : PersistentState(){
        //  constructor(stateRef: StateRef) :  this(stateRef.txhash.bytes.toHexString(), stateRef.index)
      }
  </code></pre>
  
  <blockquote>
    <p>Corda Node error Log.
        E 12:53:45 [rpc-server-handler-pool-0] vault.HibernateVaultQueryImpl._queryBy -
    org.hibernate.InstantiationException: No default constructor for
    entity:  :
    com.legalcontract.schema.LegalContractSchemaV1$PersistentLegalContractState
        E 12:53:45 [rpc-server-handler-pool-0] messaging.ObservableContext.sendMessage - Failed to send message,
    kicking client. Message was
    RpcReply(id=RpcRequestId(toLong=4982229886899153484),
    result=ErrorOr(value=null, error=org.hibernate.InstantiationException:
    No default constructor for entity:  :
    com.legalcontract.schema.LegalContractSchemaV1$PersistentLegalContractState))
         com.esotericsoftware.kryo.KryoException: Class org.hibernate.InstantiationException is not annotated or on the
    whitelist, so cannot be used in serialization
        Serialization trace:
        error (net.corda.core.ErrorOr)
                at net.corda.core.serialization.CordaClassResolver.checkClass(CordaClassResolver.kt:65)
    ~[corda-core-0.13.0.jar:?]
                at net.corda.core.serialization.CordaClassResolver.getRegistration(CordaClassResolver.kt:35)
    ~[corda-core-0.13.0.jar:?]
                at com.esotericsoftware.kryo.Kryo.getRegistration(Kryo.java:488)
    ~[kryo-4.0.0.jar:?]
                at net.corda.nodeapi.RPCKryo.getRegistration(RPCStructures.kt:74)
    ~[corda-node-api-0.13.0.jar:?]
                at com.esotericsoftware.kryo.util.DefaultClassResolver.writeClass(DefaultClassResolver.java:97)
    ~[kryo-4.0.0.jar:?]</p>
  </blockquote>