Do not move resource directories to the end of classpath (#1101)

- add integration test

integration-tests/test-classpath-project-resources/README.md

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+# Test Classpath Project Resources
+
+## Intention
+
+The intention is to test that the project test resources take priority over resources provided by libraries
+and IDE distribution JARs.
+
+## Approach
+
+The test project reproduces the usage of for mocking a final method with Mockito when the PowerMock dependency is
+additionally configured in the project.
+
+To be able to mock a final method Mockito must be provided with the inline MockMaker configuration,
+which in our case is done by the `src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker` file.
+
+When PowerMock is present, it provides its own `mockito-extensions/org.mockito.plugins.MockMaker` which can be loaded by
+Mockito, if PowerMock is before project test resource in the classpath.
+Such a situation caused the issue reported in:
+
+- https://github.com/JetBrains/gradle-intellij-plugin/issues/1101
+
+## Verification
+
+The test has two verifications:
+
+1. Project test passes when a final method is mocked with Mockito. It would fail if the test resources directory was
+   pushed after the PowerMock in the classpath.
+2. The test resources directory is before any dependency and IDE distribution JAR in the classpath. We verify IDE JARs
+   because they may provide MockMaker config in some JAR for any reason.

integration-tests/test-classpath-project-resources/build.gradle.kts

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+tasks {
+    test {
+        doFirst {
+            classpath.files.forEach {
+                println("test-classpath-project-resources: Test classpath entry: ${it.absolutePath}")
+            }
+        }
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation("junit:junit:4.13.2")
+    testImplementation("org.mockito:mockito-core:4.7.0")
+    testImplementation("org.powermock:powermock-api-mockito2:2.0.9")
+    testImplementation("org.powermock:powermock-core:2.0.9")
+}

integration-tests/test-classpath-project-resources/src/main/resources/META-INF/plugin.xml

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+<idea-plugin>
+    <id>org.jetbrains.plugins.integration-tests.test-classpath-project-resources</id>
+    <name>Any</name>
+    <vendor>Any</vendor>
+
+    <depends>com.intellij.modules.platform</depends>
+</idea-plugin>

integration-tests/test-classpath-project-resources/src/test/java/MyTest.java

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+import org.junit.Assert;
+import org.junit.Test;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class MyTest {
+
+    private final ClassWithFinalMethod testMock = mock(ClassWithFinalMethod.class);
+
+    @Test
+    public void testMockingFinalMethodWithPowerMock() {
+        String testedString = "overridden value";
+        when(testMock.finalMethod()).thenReturn(testedString);
+        String result = testMock.finalMethod();
+        Assert.assertEquals(testedString, result);
+    }
+}
+
+class ClassWithFinalMethod {
+    String finalMethod() {
+        return "final method result";
+    }
+}

integration-tests/test-classpath-project-resources/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker

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+mock-maker-inline

integration-tests/test-classpath-project-resources/verify.main.kts

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+#!/usr/bin/env -S kotlin -J-ea
+
+@file:Import("../verify.utils.kts")
+
+__FILE__.init {
+    runGradleTask("test").let { logs ->
+        val classpathEntries = logs.lines()
+            .filter { it.startsWith("test-classpath-project-resources: Test classpath entry:") }
+        val testResourcesEntryIndex = classpathEntries
+            .indexOfFirst { it.contains("/test-classpath-project-resources/build/resources/test") }
+        val powerMockDependencyEntryIndex = classpathEntries
+            .indexOfFirst { it.contains("powermock") }
+        val firstIdeJarEntryIndex = classpathEntries
+            .indexOfFirst { it.contains("/.gradle/caches/modules-2/files-2.1/com.jetbrains.intellij.idea/ideaIC/") }
+        assert(testResourcesEntryIndex < powerMockDependencyEntryIndex)
+        assert(testResourcesEntryIndex < firstIdeJarEntryIndex)
+    }
+
+}