core/src/main/java/com/orientechnologies/orient/core/serialization/serializer/string/OStringSerializerAnyStreamable.java
public StringBuilder toStream(final StringBuilder iOutput, Object iValue) {
    if (iValue != null) {
      if (!(iValue instanceof OSerializableStream))
        throw new OSerializationException("Cannot serialize the object since it's not implements the OSerializableStream interface");

      OSerializableStream stream = (OSerializableStream) iValue;
      iOutput.append(iValue.getClass().getName());
      iOutput.append(OStringSerializerEmbedded.SEPARATOR);
      iOutput.append(Base64.getEncoder().encodeToString(stream.toStream()));
    }
    return iOutput;
  }
public StringBuilder toStream(final StringBuilder iOutput, Object iValue) {
    if (iValue != null) {
      if (!(iValue instanceof OSerializableStream))
        throw new OSerializationException("Cannot serialize the object since it's not implements the OSerializableStream interface");

      OSerializableStream stream = (OSerializableStream) iValue;
      iOutput.append(iValue.getClass().getName());
      iOutput.append(OStringSerializerEmbedded.SEPARATOR);
      iOutput.append(Base64.getEncoder().encodeToString(stream.toStream()));
    }
    return iOutput;
  }
Serialize the class name size + class name + object content

@param iValue