We recently updated a Jenkins instance and noticed that in Blue Ocean, the button to `Show complete log` was missing for logs that were too large to display.

I managed to trace it to Jenkins 2.463 since 2.462 does show the button properly. I have a feeling it's related to the update letting Jetty handle the HTTP response compression.

From what I can tell, the reason the button does not show up is because in blueocean-dashboard, when rendering the page, there is a variable `hasMore` that is used to determine if the logs were cut off and if the button needs to be displayed. This variable is `true` in 2.462 but `false` in 2.463.

It seems that in 2.463 the response header no longer includes `X-Text-Size` and `X-Text-Delivered` which are used to set that variable.

I was able to easily reproduce this issue with a standard Jenkins 2.463 or later, install the Blue Ocean plugin, and create a job using the following pipeline:

pipeline {
    agent any
    
    stages {
        stage('Test') {
            steps {
                script {
                    int test = 1
                    String output = ""
                    while(test < 10000) {
                        output = "${output}\nA bunch of log text ${test += 1}"
                    }
                    echo output
                }
            }
        }
    }
}

Jenkins 2.462

Jenkins 2.463