src/CFDIReader/SchemasValidator/SchemasValidator.php
public function validateWithoutRetriever($content)
    {
        // create the schema validator object
        $validator = new SchemaValidator($content);
        if (! $validator->validate()) {
            throw new \RuntimeException('XSD error found: ' . $validator->getLastError());
        }
    }
public function validateWithoutRetriever($content)
    {
        // create the schema validator object
        $validator = new SchemaValidator($content);
        if (! $validator->validate()) {
            throw new \RuntimeException('XSD error found: ' . $validator->getLastError());
        }
    }
Validate just using the SchemaValidator, it will not retrieve any resource
and perform all validations using internet

@param string $content
@throws \RuntimeException on validation errors