Spring doesn't see h2 database hence complain about database not available - spring-webflux

Question

I'm building a simple reactive web application ( Following Josh long's tech talk ) Simply put I have reactive web, r2dbc and h2 as dependencies.
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-r2dbc</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>io.projectreactor</groupId>
<artifactId>reactor-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
So I expect spring would configure everything for me( It does for Josh ). But I get error saying not being able to connect to a database and there is a suggestion asking to include h2(which I already have). What am I doing wrong here?
Description:
Failed to configure a ConnectionFactory: 'url' attribute is not specified and no embedded database could be configured.
Reason: Failed to determine a suitable R2DBC Connection URL
Action:
Consider the following:
If you want an embedded database (H2), please put it on the classpath.
If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).

Answer 1

Ok it was missing r2dbc-h2 dependency. This happened because I didn't add r2dbc when I created the project with start.spring.io then added it and inspect the pom but only copied spring-boot-starter-data-r2dbc.
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-h2</artifactId>
<scope>runtime</scope>
</dependency>
Still bit confusing though. Spring boot says it looks in to the class path and auto configure dependencies but seems like sometimes it need given combination of dependencies.