Accept Builder to avoid build() call

Hello!

• Vote on this issue by adding a 👍 reaction
• If you want to implement this feature, comment to let us know (we'll work with you on design, scheduling, etc.)

Issue details

Could add overloads to methods accepting Foo to also accept
FooBuilder, avoiding the build() method call at the end.

Before:

ServiceArgs.builder()
    .setMetadata(ObjectMetaArgs.builder()
        .clusterName("clusterName")
        .build())

After:

ServiceArgs.builder()
    .setMetadata(ObjectMetaArgs.builder()
        .clusterName("clusterName"))

Lifting @pawelprazak's idea to an issue. We can do this, it's syntactic sugar that costs some size in the generated SDKs but may be worth it.

Affected area/feature

Start by locating the Java SDK generation code that produces methods accepting Foo and the corresponding FooBuilder, then trace how builder() and build() are represented in generated APIs. Done means callers can use the nested builder directly in examples like setMetadata without an explicit build() call, with generated SDK size considered.