public String getProperties() {
        return this.properties;
    }
<p>
A string map of event-specific data that you might choose to record. For example, if a user rates a movie on your
site, other than movie ID (<code>itemId</code>) and rating (<code>eventValue</code>) , you might also send the
number of movie ratings made by the user.
</p>
<p>
Each item in the map consists of a key-value pair. For example,
</p>
<p>
<code>{"numberOfRatings": "12"}</code>
</p>
<p>
The keys use camel case names that match the fields in the Item interactions dataset's schema. In the above
example, the <code>numberOfRatings</code> would match the 'NUMBER_OF_RATINGS' field defined in the Item
interactions dataset's schema.
</p>
<p>
The following can't be included as a keyword for properties (case insensitive).
</p>
<ul>
<li>
<p>
userId
</p>
</li>
<li>
<p>
sessionId
</p>
</li>
<li>
<p>
eventType
</p>
</li>
<li>
<p>
timestamp
</p>
</li>
<li>
<p>
recommendationId
</p>
</li>
<li>
<p>
impression
</p>
</li>
</ul>
<p>
This field's value will be valid JSON according to RFC 7159, including the opening and closing braces. For
example: '{"key": "value"}'.
</p>

@return A string map of event-specific data that you might choose to record. For example, if a user rates a movie
        on your site, other than movie ID (<code>itemId</code>) and rating (<code>eventValue</code>) , you might
        also send the number of movie ratings made by the user.</p>
        <p>
        Each item in the map consists of a key-value pair. For example,
        </p>
        <p>
        <code>{"numberOfRatings": "12"}</code>
        </p>
        <p>
        The keys use camel case names that match the fields in the Item interactions dataset's schema. In the
        above example, the <code>numberOfRatings</code> would match the 'NUMBER_OF_RATINGS' field defined in the
        Item interactions dataset's schema.
        </p>
        <p>
        The following can't be included as a keyword for properties (case insensitive).
        </p>
        <ul>
        <li>
        <p>
        userId
        </p>
        </li>
        <li>
        <p>
        sessionId
        </p>
        </li>
        <li>
        <p>
        eventType
        </p>
        </li>
        <li>
        <p>
        timestamp
        </p>
        </li>
        <li>
        <p>
        recommendationId
        </p>
        </li>
        <li>
        <p>
        impression
        </p>
        </li>
aws-java-sdk-personalizeevents/src/main/java/com/amazonaws/services/personalizeevents/model/Event.java