title: Complex Mule XPath Expression throwing exception
body: <p>I am trying to run below XPath expressions in Mule. Its giving me errors one after another.
  Can someone help me correcting these Mule XPath expressions :</p>
  
  <pre><code> &lt;xm:namespace-manager includeConfigNamespaces="true"&gt;
        &lt;xm:namespace prefix="acord" uri="ACORD.org/Standards/Life/2" /&gt;
        &lt;xm:namespace prefix="soap" uri="schemas.xmlsoap.org/soap/envelope/" /&gt;
      &lt;/xm:namespace-manager&gt;
  
      &lt;set-variable variableName="pwaHolding"
           value="#[xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc = '37']/@OriginatingObjectID').value" /&gt;
      &lt;set-variable variableName="pwaPolNumber"
           value="#[xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Holding[@id=$pwaHolding]/acord:Policy/acord:PolNumber').text]" /&gt;
  </code></pre>
  
  <p>I am getting below exception when trying to execute above XPATH expressions :</p>
  
  <pre><code>    Message  :Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException). Message payload is of type: String
      Code                  : MULE_ERROR--2
      --------------------------------------------------------------------------------
      Exception stack is:
      1. [Error: unexpected token: 37]
      [Near : {... @tc == '37']/@OriginatingObjec ....}]
                                    ^
      [Line: 1, Column: 96] (org.
  
  mvel2.CompileException)
  org.mvel2.compiler.ExpressionCompiler:247 (null)
  2. Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException)
  org.mule.el.mvel.MVELExpressionLanguage:211 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/expression/ExpressionRuntimeException.html)
  3. Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException). Message payload is of type: String (org.mule.api.transformer.TransformerMessagingException)
  org.mule.transformer.AbstractTransformer:123 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/transformer/TransformerMessagingException.html)
  --------------------------------------------------------------------------------
  Root Exception stack trace:
  [Error: unexpected token: 37]
  [Near : {... @tc == '37']/@OriginatingObjec ....}]                              ^
  [Line: 1, Column: 96]
  at org.mvel2.compiler.ExpressionCompiler._compile(ExpressionCompiler.java:247)
  at org.mvel2.util.ParseTools.subCompileExpression(ParseTools.java:1944)
  at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:862) 
  + 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything)
  </code></pre>
  
  <p>Hi David,</p>
  
  <p>I even after replacing <code>'</code> with <code>&amp;quot;</code> I am still getting below error :</p>
  
  <pre>
  Message               : Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException). Message payload is of type: String
  Code                  : MULE_ERROR--2
  --------------------------------------------------------------------------------
  Exception stack is:
  1. [Error: unexpected token: 37]
  [Near : {... @tc == '37']/@OriginatingObjec ....}]
                        ^
  [Line: 1, Column: 96] (org.mvel2.CompileException)
    org.mvel2.compiler.ExpressionCompiler:247 (null)
  2. Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException)
    org.mule.el.mvel.MVELExpressionLanguage:211 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/expression/ExpressionRuntimeException.html)
  3. Execution of the expression "xpath('//acord:TXLife/acord:TXLifeRequest/acord:OLifE/acord:Relation[acord:RelationRoleCode/@tc == '37']/@OriginatingObjectID').value" failed. (org.mule.api.expression.ExpressionRuntimeException). Message payload is of type: String (org.mule.api.transformer.TransformerMessagingException)
    org.mule.transformer.AbstractTransformer:123 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/transformer/TransformerMessagingException.html)
  </pre>
  
  <p>I have my second XPATH expression in question which is also failing. Please help me get around this as well</p>
  
  <p>
      </p>