public static EdgeLabelVerificationStrategy create(final Configuration configuration) {
        return build().throwException(configuration.getBoolean(THROW_EXCEPTION, false))
                        .logWarning(configuration.getBoolean(LOG_WARNING, false)).create();
    }
{@code EdgeLabelVerificationStrategy} does not allow edge traversal steps to have no label specified.
Providing one or more labels is considered to be a best practice, however, TinkerPop will not force the specification
of edge labels; instead, providers or users will have to enable this strategy explicitly.
<p/>

@author Daniel Kuppitz (http://gremlin.guru)
@example <pre>
__.outE()           // throws an IllegalStateException
__.out()            // throws an IllegalStateException
__.bothE()          // throws an IllegalStateException
__.to(OUT)          // throws an IllegalStateException
__.toE(IN)          // throws an IllegalStateException
</pre>
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/verification/EdgeLabelVerificationStrategy.java