Update gradle project to 7.0.2 from 5.6

I have so far been able to get the project working on 6.9 with little fuss, but am getting hung up on moving to 7.0.2 due to breaking changes, have fixed a number of them with help of the scan site, but am stuck on a

A problem occurred evaluating root project ‘projectname’.

Failed to apply plugin ‘propdeps’.
No such property: COMPILE_CONFIGURATION_NAME for class: org.gradle.api.plugins.JavaPlugin

running with --scan just shows the stacktrace with basically the same information:
org.gradle.api.GradleScriptException: A problem occurred evaluating root project ‘projectname’.
Caused by: org.gradle.api.internal.plugins.PluginApplicationException: Failed to apply plugin ‘propdeps’.
Caused by: groovy.lang.MissingPropertyException: No such property: COMPILE_CONFIGURATION_NAME for class: org.gradle.api.plugins.JavaPlugin

so it is true we have

apply plugin: ‘propdeps’
and
classpath “org.springframework.build.gradle:propdeps-plugin:0.0.7”

there doesn’t seem to be a newer propdeps to update to and the only guidance i can find on
COMPILE_CONFIGURATION_NAME is
https://gradle.github.io/kotlin-dsl-docs/api/org.gradle.api.plugins/-java-plugin/-c-o-m-p-i-l-e_-c-o-n-f-i-g-u-r-a-t-i-o-n_-n-a-m-e.html

but i have already updated the compile’s to implementation

Hello,

You have to replace the faulty version of the plugin with something compliant with Gradle 7 runtime. Since no newer version of the plugin exist, you can try to look for another candidate providing the same set of features. This plugin goal was to provide:

[…] additional optional and provided dependency configurations for Gradle along with Maven POM generation support.

These features were integrated in Gradle core features for Java projects in recent releases. So you can remove this plugin and use the Gradle core features:

okay, i commented out the propdeps plugin. I do have an optional:

optional ("org.springframework.boot:spring-boot-configuration-processor") {
    exclude group: 'com.vaadin.external.google', module: 'android-json'
}

which it is now failing on.

Could not find method optional() for arguments [org.springframework.boot:spring-boot-configuration-processor, build_exi3tvdd4n75jb5p79edd8nlj$_run_closure10$_closure19@9aaac1b] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.

trying to use https://docs.gradle.org/current/userguide/feature_variants.html#header to translate but there doesn’t seem to be such a translate guide.

commenting out the optional and I get:

Could not get unknown property 'implementationJava' for object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.

on the following line:

@kentjohnston did you find a solution to this problem ? Im having the same issue.

Which “same” are you talking about exactly?
OP showed multiple problems.
And for the original ones @Pierre1 provided guidance on how to resolve it.