code: public function getContext($exposedClassName)
      {
          $classes = $this->metadata->getAllMetadata();
          $metadata = null;
  
          foreach ($classes as $class) {
              if ($class->getExposeAs() === $exposedClassName) {
                  $metadata = $class;
                  break;
              }
          }
  
          if (null === $metadata) {
              return null;
          }
  
          $context = array(
              'hydra' => 'http://www.w3.org/ns/hydra/core#',
              'vocab' => $this->vocabUrl . '#'
          );
  
          $context[$exposedClassName] = ($metadata->isExternalReference())
              ? $metadata->getIri()
              : 'vocab:' . $metadata->getIri();
  
          foreach ($metadata->getProperties() as $property) {
              // If something is exposed as keyword, no context definition is necessary
              if (0 === strncmp($property->getExposeAs(), '@', 1)) {
                  // TODO Make this check more reliable by just checking for actual keywords
                  //      What should we do if we serialize to RDFa for instance?
                  continue;
              }
  
              $termDefinition = ($property->isExternalReference())
                  ? $property->getIri()
                  : 'vocab:' . $property->getIri();
  
              // TODO Make this check more robust
              if ($property->getRoute()) {
                  $termDefinition = array('@id' => $termDefinition, '@type' => '@id');
              } elseif ($this->hasNormalizer($property->getType())) {
                  $normalizer = $this->getNormalizer($property->getType());
                  $termDefinition = array('@id' => $termDefinition, '@type' => $normalizer->getTypeIri());
              }
  
              $context[$property->getExposeAs()] = $termDefinition;
          }
  
          return array('@context' => $context);
      }
docs: Gets the context corresponding to the passed class
  
  @param  string $exposedClassName The exposed class name
  
  @return array|null The context in the form of an associative array or
  null if no class is exposed with the specified
  name.