java.lang.NullPointerException
  at org.hibernate.engine.CollectionLoadContext.addCollectionToCache(CollectionLoadContext.java:306)
  at org.hibernate.engine.CollectionLoadContext.endLoadingCollection(CollectionLoadContext.java:203)
  at org.hibernate.engine.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:268)
  at org.hibernate.engine.CollectionLoadContext.endLoadingCollections(CollectionLoadContext.java:249)
  at org.hibernate.loader.Loader.endCollectionLoad(Loader.java:866)
  at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:853)
  at org.hibernate.loader.Loader.doQuery(Loader.java:717)
  at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
  at org.hibernate.loader.Loader.loadCollection(Loader.java:1919)
  at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:36)
  at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:520)
  at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:60)
  at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1676)
  at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:344)
  at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
  at org.hibernate.collection.PersistentList.toArray(PersistentList.java:123)
  ...

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

import org.hibernate.HibernateException;
import org.hibernate.usertype.UserType;

/**
* Removes trailing spaces to be consistent with how SQL Server does varchar
* comparisons
*/
public class TrimmedString implements UserType {

  /**
   * Returns the string without trailing spaces
   */
  private static String trimmed(String original) {
    int length = original.length();
    while (original.charAt(length - 1) == ' ') {
      length--;
    }
    return original.substring(0, length);
  }

  public Object assemble(Serializable cached, Object owner)
      throws HibernateException {
    return cached;
  }

  public Object deepCopy(Object value) throws HibernateException {
    return value;
  }

  public Serializable disassemble(Object value) throws HibernateException {
    return (Serializable) value;
  }

  public boolean equals(Object x, Object y) throws HibernateException {
    if (x == y)
      return true;
    if (null == x || null == y)
      return false;
    if (x instanceof String && y instanceof String)
      return trimmed((String) x).equals(trimmed((String) y));
    return x.equals(y);
  }

  public int hashCode(Object x) throws HibernateException {
    if (x instanceof String) {
      return trimmed((String) x).hashCode();
    } else {
      return x.hashCode();
    }
  }

  public boolean isMutable() {
    return false;
  }

  public Object nullSafeGet(ResultSet resultSet, String[] names, Object owner)
      throws HibernateException, SQLException {
    String value = resultSet.getString(names[0]);
    if (null == value)
      return null;

    return trimmed(value);
  }

  public void nullSafeSet(PreparedStatement st, Object value, int index)
      throws HibernateException, SQLException {
        st.setString(index, (String)value);
  }

  public Object replace(Object original, Object target, Object owner)
      throws HibernateException {
    return original;
  }

  public Class returnedClass() {
    return String.class;
  }

  public int[] sqlTypes() {
       return new int[] { Types.VARCHAR };
  }

}