Improve lz4-java dependency resolution strategy

Explicitly prefer Flink's at.yawk.lz4:lz4-java over org.lz4:lz4-java
to ensure the Flink-compatible version is always selected, regardless
of version numbers.

This is more robust than selectHighestVersion() which could
theoretically select org.lz4 if it had a higher version number.

Author: ddebowczyk92

runners/flink/2.1/build.gradle

@@ -43,9 +43,14 @@ project.ext {
 apply from: "../flink_runner.gradle"
 
 // Flink 2.1 uses at.yawk.lz4:lz4-java instead of org.lz4:lz4-java
-// Resolve capability conflict by preferring Flink's version
+// Explicitly prefer Flink's at.yawk.lz4 version to resolve capability conflict
 configurations.all {
   resolutionStrategy.capabilitiesResolution.withCapability('org.lz4:lz4-java') {
-    selectHighestVersion()
+    def candidate = candidates.find { it.id.toString().contains('at.yawk.lz4') }
+    if (candidate != null) {
+      select(candidate)
+    } else {
+      selectHighestVersion()
+    }
   }
 }

runners/flink/2.1/job-server/build.gradle

@@ -31,9 +31,14 @@ project.ext {
 apply from: "$basePath/flink_job_server.gradle"
 
 // Flink 2.1 uses at.yawk.lz4:lz4-java instead of org.lz4:lz4-java
-// Resolve capability conflict by preferring Flink's version
+// Explicitly prefer Flink's at.yawk.lz4 version to resolve capability conflict
 configurations.all {
   resolutionStrategy.capabilitiesResolution.withCapability('org.lz4:lz4-java') {
-    selectHighestVersion()
+    def candidate = candidates.find { it.id.toString().contains('at.yawk.lz4') }
+    if (candidate != null) {
+      select(candidate)
+    } else {
+      selectHighestVersion()
+    }
   }
 }

runners/flink/2.1/src/test/resources/flink-test-config.yaml

@@ -24,4 +24,4 @@ taskmanager:
     managed:
       size: 1gb
 parallelism:
-  default: '2'
+  default: '23'