Add REUSE compliance: LICENSES/, .reuse/dep5, and fix invalid SPDX ex… (#9)

* Add REUSE compliance: LICENSES/, .reuse/dep5, and fix invalid SPDX expressions

- Add LICENSES/Apache-2.0.txt (copy of LICENSE) as required by REUSE spec
- Add .reuse/dep5 to provide copyright/license info for files without inline headers
- Fix invalid SPDX expressions in OtelImplJavadocTest and OtelInternalJavadocTest
  by wrapping embedded SPDX-License-Identifier strings in REUSE-IgnoreStart/End
  comments to prevent the REUSE linter from treating test fixture content as
  actual license declarations

* reuse convert-dep5

Signed-off-by: Hilmar Falkenberg <hilmar.falkenberg@sap.com>

---------

Signed-off-by: Hilmar Falkenberg <hilmar.falkenberg@sap.com>

Author: hilmarf

REUSE.toml

@@ -0,0 +1,16 @@
+version = 1
+SPDX-PackageName = "OpenTelemetry Java"
+SPDX-PackageSupplier = "opentelemetry-java@googlegroups.com"
+SPDX-PackageDownloadLocation = "https://github.com/open-telemetry/opentelemetry-java"
+
+[[annotations]]
+path = "gradle/wrapper/gradle-wrapper.jar"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "Copyright Gradle, Inc."
+SPDX-License-Identifier = "Apache-2.0"
+
+[[annotations]]
+path = "**"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "Copyright The OpenTelemetry Authors"
+SPDX-License-Identifier = "Apache-2.0"

custom-checks/src/test/java/io/opentelemetry/gradle/customchecks/OtelImplJavadocTest.java

@@ -15,10 +15,12 @@ void positiveCases() {
     CompilationTestHelper.newInstance(OtelImplJavadoc.class, OtelImplJavadocTest.class)
         .addSourceLines(
             "impl/ImplJavadocPositiveCases.java",
+            // REUSE-IgnoreStart
             "/*",
             " * Copyright The OpenTelemetry Authors",
             " * SPDX-License-Identifier: Apache-2.0",
             " */",
+            // REUSE-IgnoreEnd
             "package io.opentelemetry.gradle.customchecks.impl;",
             "// BUG: Diagnostic contains: missing the required javadoc disclaimer",
             "public class ImplJavadocPositiveCases {",
@@ -36,10 +38,12 @@ void negativeCases() {
     CompilationTestHelper.newInstance(OtelImplJavadoc.class, OtelImplJavadocTest.class)
         .addSourceLines(
             "impl/ImplJavadocNegativeCases.java",
+            // REUSE-IgnoreStart
             "/*",
             " * Copyright The OpenTelemetry Authors",
             " * SPDX-License-Identifier: Apache-2.0",
             " */",
+            // REUSE-IgnoreEnd
             "package io.opentelemetry.gradle.customchecks.impl;",
             "/**",
             " * This class is not intended for use by application developers. Its API is stable and",
@@ -62,10 +66,12 @@ void nonImplPackageIgnored() {
     CompilationTestHelper.newInstance(OtelImplJavadoc.class, OtelImplJavadocTest.class)
         .addSourceLines(
             "other/NonImplPackageCases.java",
+            // REUSE-IgnoreStart
             "/*",
             " * Copyright The OpenTelemetry Authors",
             " * SPDX-License-Identifier: Apache-2.0",
             " */",
+            // REUSE-IgnoreEnd
             "package io.opentelemetry.gradle.customchecks.other;",
             "public class NonImplPackageCases {",
             "  public static class One {}",

custom-checks/src/test/java/io/opentelemetry/gradle/customchecks/OtelInternalJavadocTest.java

@@ -15,10 +15,12 @@ void positiveCases() {
     CompilationTestHelper.newInstance(OtelInternalJavadoc.class, OtelInternalJavadocTest.class)
         .addSourceLines(
             "internal/InternalJavadocPositiveCases.java",
+            // REUSE-IgnoreStart
             "/*",
             " * Copyright The OpenTelemetry Authors",
             " * SPDX-License-Identifier: Apache-2.0",
             " */",
+            // REUSE-IgnoreEnd
             "package io.opentelemetry.gradle.customchecks.internal;",
             "// BUG: Diagnostic contains: doesn't end with any of the applicable javadoc disclaimers",
             "public class InternalJavadocPositiveCases {",
@@ -36,10 +38,12 @@ void negativeCases() {
     CompilationTestHelper.newInstance(OtelInternalJavadoc.class, OtelInternalJavadocTest.class)
         .addSourceLines(
             "internal/InternalJavadocNegativeCases.java",
+            // REUSE-IgnoreStart
             "/*",
             " * Copyright The OpenTelemetry Authors",
             " * SPDX-License-Identifier: Apache-2.0",
             " */",
+            // REUSE-IgnoreEnd
             "package io.opentelemetry.gradle.customchecks.internal;",
             "/**",
             " * This class is internal and is hence not for public use. Its APIs are unstable and can change at",