public void setProperties(String properties) {
        this.properties = properties;
    }
<p>
A string map of item-specific metadata. Each element in the map consists of a key-value pair. For example,
<code>{"numberOfRatings": "12"}</code>.
</p>
<p>
The keys use camel case names that match the fields in the schema for the Items dataset. In the previous example,
the <code>numberOfRatings</code> matches the 'NUMBER_OF_RATINGS' field defined in the Items schema. For
categorical string data, to include multiple categories for a single item, separate each category with a pipe
separator (<code>|</code>). For example, <code>\"Horror|Action\"</code>.
</p>
<p>
This field's value must be valid JSON according to RFC 7159, including the opening and closing braces. For
example: '{"key": "value"}'.
</p>
<p>
The AWS SDK for Java performs a Base64 encoding on this field before sending this request to the AWS service.
Users of the SDK should not perform Base64 encoding on this field.
</p>

@param properties
       A string map of item-specific metadata. Each element in the map consists of a key-value pair. For example,
       <code>{"numberOfRatings": "12"}</code>.</p>
       <p>
       The keys use camel case names that match the fields in the schema for the Items dataset. In the previous
       example, the <code>numberOfRatings</code> matches the 'NUMBER_OF_RATINGS' field defined in the Items
       schema. For categorical string data, to include multiple categories for a single item, separate each
       category with a pipe separator (<code>|</code>). For example, <code>\"Horror|Action\"</code>.
aws-java-sdk-personalizeevents/src/main/java/com/amazonaws/services/personalizeevents/model/Item.java