File = [select id, ContentDocumentId,title,pathOnClient,versionData,FileType from ContentVersion
                       WHERE
                           title like 'Invoice%'and
                           //pathOnClient = :recordId and
                           IsLatest = true
                       ORDER BY lastmodifieddate desc
                       limit 1];

<messaging:emailTemplate subject="Here is your invoice" recipientType="Contact" relatedToType="Opportunity" >

<messaging:attachment renderAs="pdf" filename="{!relatedTo.InvoiceNumber__c +'.pdf'}">
<c:LatestInvoice />
</messaging:attachment>

"core.filemanager.FileBlobValue@787ddc4c"

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