Entities with PortableTemplateBuilder configuration are not persistable

[sjcorbett]

I had an entity configured thus:

SameServerEntity e = addChild(EntitySpec.create(SameServerEntity.class)
        .displayName("Entity")
        .configure(SameServerEntity.PROVISIONING_PROPERTIES, ImmutableMap.<String, Object>of(
                "templateBuilder", new PortableTemplateBuilder()
                    .os64Bit(true)
                    .minCores(2)
                    .minRam(8192))));

I launched Brooklyn launched with --persist auto.

XStream throws this exception when serialising the entity:

2014-04-08 16:05:20,023 WARN  Error serializing memento (attempt 1 of 5) for BasicEntityMemento{type=brooklyn.entity.basic.SameServerEntityImpl, id=YquHYAHr}; expected sometimes if attribute value modified
com.thoughtworks.xstream.converters.ConversionException: Could not call sun.net.www.http.KeepAliveCache.writeObject() : Could not call sun.net.www.http.ClientVector.writeObject() : null
---- Debugging information ----
message             : Could not call sun.net.www.http.ClientVector.writeObject()
cause-exception     : java.io.NotSerializableException
cause-message       : null
-------------------------------
message             : Could not call sun.net.www.http.KeepAliveCache.writeObject()
cause-exception     : com.thoughtworks.xstream.converters.ConversionException
cause-message       : Could not call sun.net.www.http.ClientVector.writeObject() : null
-------------------------------
    at com.thoughtworks.xstream.converters.reflection.SerializationMethodInvoker.callWriteObject(SerializationMethodInvoker.java:140) ~[xstream-1.4.3.jar:na]
Caused by: com.thoughtworks.xstream.converters.ConversionException: Could not call sun.net.www.http.ClientVector.writeObject() : null
---- Debugging information ----
message             : Could not call sun.net.www.http.ClientVector.writeObject()
cause-exception     : java.io.NotSerializableException
cause-message       : null
-------------------------------
    at com.thoughtworks.xstream.converters.reflection.SerializationMethodInvoker.callWriteObject(SerializationMethodInvoker.java:140) ~[xstream-1.4.3.jar:na]
Caused by: java.io.NotSerializableException: null
    at sun.net.www.http.ClientVector.writeObject(KeepAliveCache.java:285) ~[na:1.7.0_51]

The PortableTemplateBuilder object keeps a reference to a Jclouds ComputeService. A long way down the serialisation chain this causes a Thread to be serialised, which causes XStream to fail.

My workaround has been to swap the template builder with direct configuration of the properties:

        .configure(SameServerEntity.PROVISIONING_PROPERTIES, ImmutableMap.<String, Object>of(
                JcloudsLocationConfig.MIN_RAM.getName(), 8192,
                JcloudsLocationConfig.MIN_CORES.getName(), 2,
                JcloudsLocationConfig.OS_64_BIT.getName(), true)