public boolean isExplicitHttp2() {
        return this == H2 || this == H2C;
    }
Returns {@code true} if this {@link SessionProtocol} is {@link #H2} or {@link #H2C}.
Note that this method returns {@code false} for {@link #HTTP} and {@link #HTTPS}.
core/src/main/java/com/linecorp/armeria/common/SessionProtocol.java