Introduce RequestParamAnnotationCheck for invalid types

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/RequestParamTypeCheck.java

@@ -0,0 +1,45 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableCollection;
+import com.google.common.collect.ImmutableMap;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.VariableTree;
+
+/** A {@link BugChecker} which flags {@code @RequestParam} parameters with an unsupported type. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    name = "RequestParamType",
+    summary = "`@RequestParam` does not support `ImmutableCollection` and `ImmutableMap` subtypes",
+    linkType = NONE,
+    severity = ERROR,
+    tags = LIKELY_ERROR)
+public final class RequestParamTypeCheck extends BugChecker implements VariableTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<VariableTree> HAS_UNSUPPORTED_REQUEST_PARAM =
+      allOf(
+          annotations(AT_LEAST_ONE, isType("org.springframework.web.bind.annotation.RequestParam")),
+          anyOf(isSubtypeOf(ImmutableCollection.class), isSubtypeOf(ImmutableMap.class)));
+
+  @Override
+  public Description matchVariable(VariableTree tree, VisitorState state) {
+    return HAS_UNSUPPORTED_REQUEST_PARAM.matches(tree, state)
+        ? describeMatch(tree)
+        : Description.NO_MATCH;
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RequestParamTypeCheckTest.java

@@ -0,0 +1,53 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class RequestParamTypeCheckTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(RequestParamTypeCheck.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "A.java",
+            "import com.google.common.collect.ImmutableBiMap;",
+            "import com.google.common.collect.ImmutableList;",
+            "import com.google.common.collect.ImmutableMap;",
+            "import com.google.common.collect.ImmutableSet;",
+            "import java.util.List;",
+            "import java.util.Map;",
+            "import java.util.Set;",
+            "import javax.annotation.Nullable;",
+            "import org.springframework.web.bind.annotation.DeleteMapping;",
+            "import org.springframework.web.bind.annotation.GetMapping;",
+            "import org.springframework.web.bind.annotation.PostMapping;",
+            "import org.springframework.web.bind.annotation.PutMapping;",
+            "import org.springframework.web.bind.annotation.RequestBody;",
+            "import org.springframework.web.bind.annotation.RequestParam;",
+            "",
+            "interface A {",
+            "  @PostMapping A properRequestParam(@RequestBody String body);",
+            "  @GetMapping A properRequestParam(@RequestParam int param);",
+            "  @GetMapping A properRequestParam(@RequestParam List<String> param);",
+            "  @PostMapping A properRequestParam(@RequestBody String body, @RequestParam Set<String> param);",
+            "  @PutMapping A properRequestParam(@RequestBody String body, @RequestParam Map<String, String> param);",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @GetMapping A get(@RequestParam ImmutableBiMap<String, String> param);",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @PostMapping A post(@Nullable @RequestParam ImmutableList<String> param);",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @PutMapping A put(@RequestBody String body, @RequestParam ImmutableSet<String> param);",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @DeleteMapping A delete(@RequestBody String body, @RequestParam ImmutableMap<String, String> param);",
+            "",
+            "  void negative(ImmutableSet<Integer> set, ImmutableMap<String, String> map);",
+            "}")
+        .doTest();
+  }
+}