aeron-client/src/main/java/io/aeron/ChannelUriStringBuilder.java
public ChannelUriStringBuilder prefix(final String prefix)
    {
        if (null != prefix && !prefix.equals("") && !prefix.equals(SPY_QUALIFIER))
        {
            throw new IllegalArgumentException("invalid prefix: " + prefix);
        }

        this.prefix = prefix;
        return this;
    }
public ChannelUriStringBuilder prefix(final String prefix)
    {
        if (null != prefix && !prefix.equals("") && !prefix.equals(SPY_QUALIFIER))
        {
            throw new IllegalArgumentException("invalid prefix: " + prefix);
        }

        this.prefix = prefix;
        return this;
    }
Set the prefix for taking an addition action such as spying on an outgoing publication with "aeron-spy".

@param prefix to be applied to the URI before the the scheme.
@return this for a fluent API.
@see ChannelUri#SPY_QUALIFIER