@Override
    public void apply(final Traversal.Admin<?, ?> traversal) {
        if (traversal.getStrategies().toList().contains(VertexProgramStrategy.instance())) {
            throw new VerificationException("The TraversalSource does not allow the use of a GraphComputer", traversal);
        }
    }
Detects the presence of a {@link VertexProgramStrategy} and throws an {@link IllegalStateException} if it is found.

@author Marc de Lignie
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/traversal/strategy/verification/VertexProgramRestrictionStrategy.java