@Override
	protected String toDSL() {
		StringBuilder dslBuilder = new StringBuilder();
		dslBuilder.append("gemfire");
		dslBuilder.append(" --useLocator=" + useLocator);
		dslBuilder.append(" --host=" + host);
		dslBuilder.append(" --port=" + port);
		dslBuilder.append(" --regionName=" + region);
		if (cacheEventExpression != null) {
			dslBuilder.append(" --cacheEventExpression=" + cacheEventExpression);
		}

		return dslBuilder.toString();
	}
Set the cache key. Defaults to stream name

@param cacheEventExpression a SpEL expression evaluating the payload
@return this
spring-xd-test-fixtures/src/main/java/org/springframework/xd/test/fixtures/GemFireSource.java