Fix entity decoding from expressions in operation chain

[OperationActionBean] org.nuxeo.ecm.automation.OperationException: Failed to invoke operation Document.SetProperty
org.nuxeo.ecm.automation.OperationException: Failed to invoke operation Document.SetProperty
...
Caused by: [Error: could not access: amp; in class: null]
[Near : {... Unknown ....}]
             ^
[Line: 1, Column: 0]
	at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getBeanProperty(ReflectiveAccessorOptimizer.java:611)
	at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:323)
	at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:135)
	at org.mvel2.optimizers.dynamic.DynamicOptimizer.optimizeAccessor(DynamicOptimizer.java:66)
	at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:139)
	at org.mvel2.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:111)
	at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85)
	at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:108)
	at org.mvel2.MVEL.executeExpression(MVEL.java:1057)
	at org.nuxeo.ecm.automation.core.scripting.MvelExpression.eval(MvelExpression.java:38)
	at org.nuxeo.ecm.automation.core.impl.OperationTypeImpl.inject(OperationTypeImpl.java:164)
	at org.nuxeo.ecm.automation.core.impl.OperationTypeImpl.newInstance(OperationTypeImpl.java:155)
	at org.nuxeo.ecm.automation.core.impl.InvokableMethod.doInvoke(InvokableMethod.java:114)
	at org.nuxeo.ecm.automation.core.impl.InvokableMethod.invoke(InvokableMethod.java:132)
	... 110 more