Excavator: Apply Gradle Plugin Testing Helper (#733)

build.gradle

@@ -25,6 +25,7 @@ buildscript {
         classpath 'com.palantir.jakartapackagealignment:jakarta-package-alignment:0.6.0'
         classpath 'com.palantir.gradle.jdks:gradle-jdks:0.48.0'
         classpath 'com.palantir.gradle.jdkslatest:gradle-jdks-latest:0.13.0'
+        classpath 'com.palantir.gradle.plugintesting:gradle-plugin-testing:0.5.0'
         classpath 'com.gradle.publish:plugin-publish-plugin:1.3.0'
         classpath 'com.palantir.baseline:gradle-baseline-java:6.9.0'
         classpath 'com.palantir.gradle.consistentversions:gradle-consistent-versions:2.25.0'
@@ -51,6 +52,7 @@ apply plugin: 'com.palantir.external-publish-gradle-plugin'
 apply plugin: 'com.palantir.external-publish-jar'
 apply plugin: 'com.palantir.failure-reports'
 apply plugin: 'com.palantir.git-version'
+apply plugin: 'com.palantir.gradle-plugin-testing'
 apply plugin: 'com.palantir.java-format'
 apply plugin: 'com.palantir.jdks'
 apply plugin: 'com.palantir.jdks.latest'

versions.lock

@@ -2,13 +2,21 @@
 
 [Test dependencies]
 cglib:cglib-nodep:3.2.2 (1 constraints: 490ded24)
+com.google.code.findbugs:jsr305:3.0.2 (1 constraints: 170aecb4)
+com.google.errorprone:error_prone_annotations:2.36.0 (1 constraints: 4d0a49bf)
+com.google.guava:failureaccess:1.0.2 (1 constraints: 150ae2b4)
+com.google.guava:guava:33.4.0-jre (2 constraints: d31e797d)
+com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava (1 constraints: bd17c918)
+com.google.j2objc:j2objc-annotations:3.0.0 (1 constraints: 150aeab4)
 com.netflix.nebula:nebula-test:10.6.2 (1 constraints: 3b053b3b)
+com.palantir.gradle.plugintesting:plugin-testing-core:0.5.0 (1 constraints: 0705fa35)
 com.squareup.okhttp3:mockwebserver:4.12.0 (1 constraints: 3905413b)
 com.squareup.okhttp3:okhttp:4.12.0 (1 constraints: 660fa27c)
 com.squareup.okio:okio:3.6.0 (1 constraints: 530c38fd)
 com.squareup.okio:okio-jvm:3.6.0 (1 constraints: 500ad3b9)
 junit:junit:4.13.2 (2 constraints: 831d9940)
 org.apiguardian:apiguardian-api:1.1.2 (2 constraints: 5523ed36)
+org.checkerframework:checker-qual:3.43.0 (1 constraints: 4c0a4abf)
 org.codehaus.groovy:groovy:3.0.12 (2 constraints: 781b1f9d)
 org.hamcrest:hamcrest:2.2 (1 constraints: d20cdc04)
 org.hamcrest:hamcrest-core:1.3 (1 constraints: cc05fe3f)