http input not working after upgrading to logstash 8.17.2

[svanherck]

Logstash information:

Please include the following information:

1. Logstash version: 8.17.2

OS version (uname -a if on a Unix-like system): Rocky 9.5
Description of the problem including expected versus actual behavior:

After upgrading logstash from 8.14.3 to 8.17.2, a logstash pipeline with elastic serverless forwarder plugin won't startup anymore. Problem seems to be in underlying http_inut plugin (see included log)

Steps to reproduce:

1. Upgrade to logstash version 8.17.2
2. Start pipeline with elastic serverless forwarder plugin
   Input config:

input {
  elastic_serverless_forwarder {
    port => 50450
    ssl => false
  }

Provide logs (if relevant):

[2025-04-01T13:40:14,728][ERROR][logstash.inputs.http ] unable to process event. {:message=>"class org.jruby.RubyNil cannot be cast to class org.jruby.RubyString (org.jruby.RubyNil and org.jruby.RubyString are in unnamed module of loader 'app')", :class=>"Java::JavaLang::ClassCastException", :backtrace=>["org.logstash.common.BufferedTokenizerExt.extract(BufferedTokenizerExt.java:122)", "usr.share.logstash.vendor.bundle.jruby.$3_dot_1_dot_0.gems.logstash_minus_codec_minus_json_lines_minus_3_dot_2_dot_2.lib.logstash.codecs.json_lines.RUBY$method$decode$0(/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-codec-json_lines-3.2.2/lib/logstash/codecs/json_lines.rb:69)", "usr.share.logstash.vendor.bundle.jruby.$3_dot_1_dot_0.gems.logstash_minus_codec_minus_json_lines_minus_3_dot_2_dot_2.lib.logstash.codecs.json_lines.RUBY$method$decode$0$VARARGS(/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-codec-json_lines-3.2.2/lib/logstash/codecs/json_lines.rb:68)", "org.jruby.internal.runtime.methods.CompiledIRMethod.call(CompiledIRMethod.java:139)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.call(MixedModeIRMethod.java:112)", "org.jruby.ir.targets.indy.InvokeSite.performIndirectCall(InvokeSite.java:725)", "org.jruby.ir.targets.indy.InvokeSite.invoke(InvokeSite.java:657)", "usr.share.logstash.vendor.bundle.jruby.$3_dot_1_dot_0.gems.logstash_minus_input_minus_http_minus_3_dot_10_dot_1_minus_java.lib.logstash.inputs.http.RUBY$method$decode_body$0(/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-input-http-3.10.1-java/lib/logstash/inputs/http.rb:243)", "usr.share.logstash.vendor.bundle.jruby.$3_dot_1_dot_0.gems.logstash_minus_input_minus_http_minus_3_dot_10_dot_1_minus_java.lib.logstash.inputs.http.RUBY$method$decode_body$0$VARARGS(/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-input-http-3.10.1-java/lib/logstash/inputs/http.rb:240)", "org.jruby.internal.runtime.methods.CompiledIRMethod.call(CompiledIRMethod.java:139)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.call(MixedModeIRMethod.java:112)", "org.jruby.ir.targets.indy.InvokeSite.performIndirectCall(InvokeSite.java:735)", "org.jruby.ir.targets.indy.InvokeSite.invoke(InvokeSite.java:657)", "usr.share.logstash.vendor.bundle.jruby.$3_dot_1_dot_0.gems.logstash_minus_input_minus_http_minus_3_dot_10_dot_1_minus_java.lib.logstash.inputs.http.message_handler.RUBY$method$onNewMessage$0(/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-input-http-3.10.1-java/lib/logstash/inputs/http/message_handler.rb:30)", "usr.share.logstash.vendor.bundle.jruby.$3_dot_1_dot_0.gems.logstash_minus_input_minus_http_minus_3_dot_10_dot_1_minus_java.lib.logstash.inputs.http.message_handler.RUBY$method$onNewMessage$0$VARARGS(/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-input-http-3.10.1-java/lib/logstash/inputs/http/message_handler.rb:29)", "org.jruby.internal.runtime.methods.CompiledIRMethod.call(CompiledIRMethod.java:139)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.call(MixedModeIRMethod.java:112)", "org.jruby.gen.LogStash$$Inputs$$Http$$MessageHandler_1179617456.onNewMessage(org/jruby/gen/LogStash$$Inputs$$Http$$MessageHandler_1179617456.gen:13)", "org.logstash.plugins.inputs.http.util.ExecutionObservingMessageHandler.lambda$onNewMessage$0(ExecutionObservingMessageHandler.java:26)", "org.logstash.plugins.inputs.http.util.ExecutionObserver.observeExecution(ExecutionObserver.java:98)", "org.logstash.plugins.inputs.http.util.ExecutionObservingMessageHandler.onNewMessage(ExecutionObservingMessageHandler.java:26)", "org.logstash.plugins.inputs.http.MessageProcessor.processMessage(MessageProcessor.java:77)", "org.logstash.plugins.inputs.http.MessageProcessor.run(MessageProcessor.java:62)", "java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)", "java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)", "java.base/java.lang.Thread.run(Thread.java:1583)"]}