UnsupportedOperationException at startup when using JDK 26+

从 co.elastic.apm.agent.bci.IndyBootstrap#loadClassInBootstrap 开始，检查它如何调用 Byte Buddy 的 ClassInjector。将该路径与所引用的 OpenTelemetry HelperInjector 实现进行比较，然后在 JDK 26 或更高版本上复现 agent 启动。完成的标准是：启动不再因报告的 UnsupportedOperationException 而失败，且不依赖临时的 system-property workaround。

Initially reported in our forum.

2026-06-25 17:22:20,878 [main] ERROR co.elastic.apm.agent.bci.ElasticApmAgent - Exception occurred while applying instrumentation co.elastic.apm.agent.java_ldap.LdapClientInstrumentation
java.lang.RuntimeException: java.lang.UnsupportedOperationException: Could not access Unsafe class: As of Java 26, using Unsafe is disabled by default, set net.bytebuddy.safe to true if you want to use the JVM's internal unsafe API even though it will become unsupported in the future and should be replaced by injection using method handles: net.bytebuddy.dynamic.loading.ClassInjector$UsingLookup
        at co.elastic.apm.agent.bci.IndyBootstrap.getIndyBootstrapMethod(IndyBootstrap.java:240) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.ElasticApmAgent.getTransformer(ElasticApmAgent.java:486) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.ElasticApmAgent.applyAdvice(ElasticApmAgent.java:444) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.ElasticApmAgent.initAgentBuilder(ElasticApmAgent.java:365) [elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.ElasticApmAgent.initInstrumentation(ElasticApmAgent.java:290) [elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.ElasticApmAgent.initInstrumentation(ElasticApmAgent.java:179) [elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.ElasticApmAgent.initialize(ElasticApmAgent.java:165) [elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104) ~[?:?]
        at java.lang.reflect.Method.invoke(Method.java:565) ~[?:?]
        at co.elastic.apm.agent.premain.AgentMain.loadAndInitializeAgent(AgentMain.java:157) [elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.premain.AgentMain.init(AgentMain.java:98) [elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.premain.AgentMain.premain(AgentMain.java:47) [elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104) ~[?:?]
        at java.lang.reflect.Method.invoke(Method.java:565) ~[?:?]
        at sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:544) [?:?]
        at sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:556) [?:?]
Caused by: java.lang.UnsupportedOperationException: Could not access Unsafe class: As of Java 26, using Unsafe is disabled by default, set net.bytebuddy.safe to true if you want to use the JVM's internal unsafe API even though it will become unsupported in the future and should be replaced by injection using method handles: net.bytebuddy.dynamic.loading.ClassInjector$UsingLookup
        at net.bytebuddy.dynamic.loading.ClassInjector$UsingUnsafe$Dispatcher$Unavailable.initialize(ClassInjector.java:2206) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at net.bytebuddy.dynamic.loading.ClassInjector$UsingUnsafe.injectRaw(ClassInjector.java:1907) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at net.bytebuddy.dynamic.loading.ClassInjector$AbstractBase.injectRaw(ClassInjector.java:202) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.IndyBootstrap.loadClassInBootstrap(IndyBootstrap.java:310) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.IndyBootstrap.initIndyBootstrap(IndyBootstrap.java:268) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        at co.elastic.apm.agent.bci.IndyBootstrap.getIndyBootstrapMethod(IndyBootstrap.java:234) ~[elastic-apm-agent-1.56.1-SNAPSHOT.jar:1.56.1-SNAPSHOT]
        ... 15 more

I think we need to modify the call to ClassInjector inco.elastic.apm.agent.bci.IndyBootstrap#loadClassInBootstrap method to implement something close to what is being done in upstream otel in https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/31188f0f8190356f8b943c81a0c8c51e9a45e6c4/muzzle/src/main/java/io/opentelemetry/javaagent/tooling/HelperInjector.java#L391

As reference, here is the PR that mainly contributed to the current version (where Unsafe usages were being removed) : https://github.com/open-telemetry/opentelemetry-java-instrumentation/pull/14855

The temporary workaround is to set net.bytebuddy.safe = false in Java system properties by adding the -Dnet.bytebuddy.safe=false JVM command line argument.