Android regression in okhttp instrumentation in 1.7.0

[jkwatson]

Describe the bug
It appears that the okhttp3 instrumentation released in v1.7.0 contains a usage of java's MethodHandle which is not supported on Android before API level 'O' (API level 26).

Steps to reproduce
Do an android app build using the v1.7.0-alpha version of the okhttp3 instrumentation. Example build failure is here: signalfx/splunk-otel-android#176

What did you expect to see?
The build to succeed, and the Android gradle plugin is able to generate Android bytecode.

What did you see instead?

ERROR:/Users/jwatson/.gradle/caches/modules-2/files-2.1/io.opentelemetry.instrumentation/opentelemetry-instrumentation-api/1.7.0-alpha/d5e265ff68ba58266a61ef62730e142e32635a3f/opentelemetry-instrumentation-api-1.7.0-alpha.jar: D8: com.android.tools.r8.internal.n1: MethodHandle.invoke and MethodHandle.invokeExact are only supported starting with Android O (--min-api 26)

What version are you using?
v1.7.0-alpha

Environment
Android Gradle Plugin version 7.0.3, targetting Android API level 21.

Additional context
N/A

[jkwatson]

Unfortunately, this didn't fix the issue completely. Re-opening to track the continuing work.

[jkwatson]

New runtime issue (build works fine now):

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.splunk.android.sample, PID: 16867
    java.lang.NoClassDefFoundError: Failed resolution of: Ljava/lang/ClassValue;
        at io.opentelemetry.instrumentation.api.internal.RuntimeVirtualFieldSupplier.get(RuntimeVirtualFieldSupplier.java:39)
        at io.opentelemetry.instrumentation.api.field.VirtualField.find(VirtualField.java:40)
        at io.opentelemetry.instrumentation.okhttp.v3_0.TracingCallFactory.<clinit>(TracingCallFactory.java:25)
        at io.opentelemetry.instrumentation.okhttp.v3_0.OkHttpTracing.newCallFactory(OkHttpTracing.java:68)

[laurit]

Fixed in 1.9.0