@ModuleOption("the protocol to use to retrieve messages")
	public void setProtocol(MailProtocol protocol) {
		this.protocol = protocol;
		if (protocol == imaps) {
			this.defaultProperties = IMAPS_PROPERTIES;
		}
	}
Captures options for the {@code mail} source module.

@author Eric Bottard
@author Gary Russell
@author Ilayaperumal Gopinathan
extensions/spring-xd-extension-mail/src/main/java/org/springframework/xd/mail/MailSourceOptionsMetadata.java