Make ClientRequestContext.authority() and host() return non-null

[chickenchickenlove]

Motivation:

• If host(), authority() never return null, host(), authority() will become stableAPI.

Modifications:

• host(), authority() of ClientRequestContext will throw IllegalStateException if host, authority are null.
• Remove annotations @UnstableAPI, @Nullable from host(), authority().
• Rearrange a little bit in autoFillSchemeAuthorityAndOrigin(). (It can be called during initialization of ClientRequestContext)
• Add a test case.

Result:

• Closes Make ClientRequestContext.authority() and host() return non-null #5552

[github-actions]

🔍 Build Scan® (commit: 392c249)

Job name	Status	Build Scan®
build-ubicloud-standard-8-jdk-8	❌ (failure)	https://ge.armeria.dev/s/7tnsr64tp35ww
build-ubicloud-standard-8-jdk-21-snapshot-blockhound	✅	https://ge.armeria.dev/s/qqi5isyzytrjc
build-ubicloud-standard-8-jdk-17-min-java-17-coverage	❌ (failure)	https://ge.armeria.dev/s/ucfgcjxwtlk3a
build-ubicloud-standard-8-jdk-17-min-java-11	✅	https://ge.armeria.dev/s/uz4gm3g73nqhi
build-ubicloud-standard-8-jdk-17-leak	❌ (failure)	https://ge.armeria.dev/s/oy7ypjaojc3dy
build-ubicloud-standard-8-jdk-11	✅	https://ge.armeria.dev/s/zw72d4vzms4si
build-macos-12-jdk-21	✅	https://ge.armeria.dev/s/ywd5xwraeqoxs

[ikhoon]

Q) Did you change this because some were tests broken?

[chickenchickenlove]

Yes, a test case testEmptyEndpointTags() in BraveClientTest.class failed.

// BraveClientTest.class
void testEmptyEndpointTags() {
    ...
    // expected: "UNKNOWN"
    // but was: null
    assertThat(span.tag("http.host")).isEqualTo("UNKNOWN"); <--- Assertion Error
}

[ikhoon]

The implementations of this class are not related to ClientRequestContext.
Would rename it to ObjectUtil?

[ikhoon]

Armeria uses @NonNullByDefault annotation so CheckForNull is unnecessary.

Suggested change

	public static <T> T firstNonNullException(@CheckForNull Supplier<T> firstSupplier, @CheckForNull T second) {
	public static <T> T firstNonNullException(Supplier<T> firstSupplier, T second) {

[chickenchickenlove]

Thanks for your comments!
I didn't know that at all 🙇‍♂️

[ikhoon]

What do you think of creating a private method to a nullable value instead of catching the exception?

@Nullable
private String authorityOrNull();

[chickenchickenlove]

Wow, It is better way!
@ikhoon nim, I have a question.
Should the methods authority() and host() throw a CheckedException so that the user is forced to handle the error?

IMHO, I think UncheckedException is better than CheckedException in case. because it's easy to read.