Replace RuntimeException with FlagsmithRuntimeError (#130)

src/main/java/com/flagsmith/FlagsmithApiWrapper.java

@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import com.flagsmith.config.FlagsmithConfig;
+import com.flagsmith.exceptions.FlagsmithRuntimeError;
 import com.flagsmith.flagengine.environments.EnvironmentModel;
 import com.flagsmith.flagengine.features.FeatureStateModel;
 import com.flagsmith.flagengine.identities.traits.TraitModel;
@@ -159,7 +160,7 @@ public Flags getFeatureFlags(boolean doThrow) {
     } catch (ExecutionException ee) {
       logger.error("Execution failed on fetching Feature flags.", ee);
       if (doThrow) {
-        throw new RuntimeException(ee);
+        throw new FlagsmithRuntimeError(ee);
       }
     }
 
@@ -232,7 +233,7 @@ public Flags identifyUserWithTraits(
     } catch (ExecutionException ee) {
       logger.error("Execution failed on fetching Feature flags.", ee);
       if (doThrow) {
-        throw new RuntimeException(ee);
+        throw new FlagsmithRuntimeError(ee);
       }
     }
 
@@ -258,7 +259,7 @@ public EnvironmentModel getEnvironment() {
       logger.error("Environment loading interrupted.", ie);
     } catch (ExecutionException ee) {
       logger.error("Execution failed on Environment loading.", ee);
-      throw new RuntimeException(ee);
+      throw new FlagsmithRuntimeError(ee);
     }
 
     return null;

src/main/java/com/flagsmith/FlagsmithClient.java

@@ -4,6 +4,7 @@
 import com.flagsmith.config.FlagsmithConfig;
 import com.flagsmith.exceptions.FlagsmithApiError;
 import com.flagsmith.exceptions.FlagsmithClientError;
+import com.flagsmith.exceptions.FlagsmithRuntimeError;
 import com.flagsmith.flagengine.Engine;
 import com.flagsmith.flagengine.environments.EnvironmentModel;
 import com.flagsmith.flagengine.features.FeatureStateModel;
@@ -478,7 +479,7 @@ public FlagsmithClient build() {
 
       if (configuration.getEnableLocalEvaluation()) {
         if (!apiKey.startsWith("ser.")) {
-          throw new RuntimeException(
+          throw new FlagsmithRuntimeError(
               "In order to use local evaluation, please generate a server key "
                   + "in the environment settings page.");
         }

src/main/java/com/flagsmith/exceptions/FlagsmithRuntimeError.java

@@ -0,0 +1,23 @@
+package com.flagsmith.exceptions;
+
+/*
+ * Custom RuntimeException for use in the Flagsmith client code.
+ *
+ * TODO: this only extends RuntimeException to maintain backwards compatibility
+ *  for any implementations that previously caught RuntimeException. We should
+ *  consider changing this in a future major release since it's unnecessary.
+ */
+public class FlagsmithRuntimeError extends RuntimeException {
+
+  public FlagsmithRuntimeError() {
+    super();
+  }
+
+  public FlagsmithRuntimeError(String message) {
+    super(message);
+  }
+
+  public FlagsmithRuntimeError(Throwable cause) {
+    super(cause);
+  }
+}

src/main/java/com/flagsmith/threads/RequestProcessor.java

@@ -7,12 +7,13 @@
 import com.flagsmith.MapperFactory;
 import com.flagsmith.config.Retry;
 import com.flagsmith.exceptions.FlagsmithApiError;
+import com.flagsmith.exceptions.FlagsmithRuntimeError;
+
 import java.io.IOException;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
-import lombok.Data;
 import okhttp3.Call;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
@@ -104,7 +105,7 @@ public <T> Future<T> executeAsync(
           localRetry.retryAttempted();
         } while (localRetry.isRetry(statusCode));
       } catch (Exception e) {
-        throw new RuntimeException();
+        throw new FlagsmithRuntimeError();
       } finally {
         if (!completableFuture.isDone()) {
           if (doThrow) {