@Override
    public IterationRuntimeContext getIterationRuntimeContext() {
        if (this.runtimeContext == null) {
            throw new IllegalStateException("The runtime context has not been initialized.");
        } else if (this.runtimeContext instanceof IterationRuntimeContext) {
            return (IterationRuntimeContext) this.runtimeContext;
        } else {
            throw new IllegalStateException("This stub is not part of an iteration step function.");
        }
    }
Reason:
Date: 2018/10/18
Company: www.dtstack.com
@author xuchao
core/src/main/java/com/dtstack/flink/sql/watermarker/AbstractCustomerWaterMarker.java