Fixing `Could not determine java version from '11.0.5'.`

I was trying to run a Java application when I got this error:

# ./gradlew run

FAILURE: Build failed with an exception.

* What went wrong:
Could not determine java version from '11.0.5'.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
root@ubuntu-512mb-sfo1-01:~/KOMORANRestAPIServer# cat build.gradle 

Posts on StackOverflow suggest many things like updating Gradle with this command ./gradlew wrapper --gradle-version 6.0.1. But running it gives the same error:

# ./gradlew wrapper --gradle-version 6.0.1


FAILURE: Build failed with an exception.

* What went wrong:
Could not determine java version from '11.0.5'.

I had to manually change the version in gradle/wrapper/gradle-wrapper.properties. Once I did, Gradle ran correctly:

# ./gradlew run
Downloading https://services.gradle.org/distributions/gradle-6.0.1-bin.zip
...........................................................................................................................................................................................................................................................
Unzipping /root/.gradle/wrapper/dists/gradle-6.0.1-bin/1lxlpkiy24sb18odw96cp4ojv/gradle-6.0.1-bin.zip to /root/.gradle/wrapper/dists/gradle-6.0.1-bin/1lxlpkiy24sb18odw96cp4ojv
Set executable permissions for: /root/.gradle/wrapper/dists/gradle-6.0.1-bin/1lxlpkiy24sb18odw96cp4ojv/gradle-6.0.1/bin/gradle

Welcome to Gradle 6.0.1!

Here are the highlights of this release:
 - Substantial improvements in dependency management, including
   - Publishing Gradle Module Metadata in addition to pom.xml
   - Advanced control of transitive versions
   - Support for optional features and dependencies
   - Rules to tweak published metadata
 - Support for Java 13
 - Faster incremental Java and Groovy compilation
 - New Zinc compiler for Scala
 - VS2019 support
 - Support for Gradle Enterprise plugin 3.0

For more details see https://docs.gradle.org/6.0.1/release-notes.html

Starting a Gradle Daemon (subsequent builds will be faster)

> Task :run
...