docs: clarify HttpLogLevel.fromEnv layering and use enum-driven lookup

The fromEnv KDoc described env-only resolution, but the value is read
through Configuration.get, which layers override -> env var -> normalized
system property -> default. Note this so callers aren't surprised when a
system property supplies the value.

Replace the hardcoded when over level-name string literals with a lookup
over HttpLogLevel.entries so a newly added enum constant resolves without
a matching branch edit. Add a test pinning that a whitespace-only value
falls back to the supplied default.

Author: OmarAlJarrah

sdk-core/src/main/kotlin/org/dexpace/sdk/core/http/pipeline/steps/HttpLogLevel.kt

@@ -37,8 +37,14 @@ public enum class HttpLogLevel {
 
     public companion object {
         /**
-         * Resolves a log level from the environment-variable [key], reading through the testable
-         * env-source seam of [source].
+         * Resolves a log level from the configuration [key], reading through the testable
+         * config seam of [source].
+         *
+         * Despite the name, resolution is not env-only: [source] is consulted via
+         * [Configuration.get], which applies the full layering — explicit override -> environment
+         * variable -> normalized system property -> default. So the value may legitimately come
+         * from an override or from a system property (e.g. the key `MY_PRODUCT_LOG_LEVEL` also
+         * matches the `my.product.log.level` system property), not strictly the environment.
          *
          * The SDK is a toolkit, not a product, so it deliberately bakes in **no** default key —
          * the caller (e.g. a generated client) supplies its own product's variable name, and
@@ -61,12 +67,8 @@ public enum class HttpLogLevel {
             default: HttpLogLevel = NONE,
         ): HttpLogLevel {
             val raw = source.get(key) ?: return default
-            return when (raw.trim().uppercase(Locale.US)) {
-                "NONE" -> NONE
-                "HEADERS" -> HEADERS
-                "BODY_AND_HEADERS" -> BODY_AND_HEADERS
-                else -> default
-            }
+            val name = raw.trim().uppercase(Locale.US)
+            return entries.firstOrNull { it.name == name } ?: default
         }
     }
 }

sdk-core/src/test/kotlin/org/dexpace/sdk/core/http/pipeline/steps/HttpLogLevelTest.kt

@@ -77,6 +77,17 @@ class HttpLogLevelTest {
         )
     }
 
+    @Test
+    fun `whitespace-only value returns the supplied default`() {
+        // Configuration only treats an exactly-empty env string as absent, so a whitespace-only
+        // value is returned as-is; fromEnv's own trim collapses it to "" and falls to the default.
+        val cfg = configWithEnv("MY_PRODUCT_LOG_LEVEL" to "   ")
+        assertEquals(
+            HttpLogLevel.HEADERS,
+            HttpLogLevel.fromEnv("MY_PRODUCT_LOG_LEVEL", cfg, HttpLogLevel.HEADERS),
+        )
+    }
+
     // ----- Unrecognized value falls back to the supplied default -----
 
     @Test