Method checkInPlan

src/org/apache/pig/impl/plan/OperatorPlan.java:412–419

(E op)

    }

    private void checkInPlan(E op) throws PlanException {
        if (mOps.get(op) == null) {
            PlanException pe = new PlanException("Attempt to connect operator " +
                op.name() + " which is not in the plan.");
            log.error(pe.getMessage());
            throw pe;
        }
    }
    
    /**
     * Merges the operators in the incoming operPlan with