### Question:
OpenTelemetry { public static MeterProvider getMeterProvider() { return getInstance().meterProvider; } private  OpenTelemetry(); static TracerProvider getTracerProvider(); static Tracer getTracer(String instrumentationName); static Tracer getTracer(String instrumentationName, String instrumentationVersion); static MeterProvider getMeterProvider(); static Meter getMeter(String instrumentationName); static Meter getMeter(String instrumentationName, String instrumentationVersion); static BaggageManager getBaggageManager(); static ContextPropagators getPropagators(); static void setPropagators(ContextPropagators propagators);  }### Answer:
@Test void testMeterLoadArbitrary() throws IOException { File serviceFile = createService( MeterProviderFactory.class, FirstMeterProviderFactory.class, SecondMeterProviderFactory.class); try { assertTrue( (OpenTelemetry.getMeterProvider() instanceof FirstMeterProviderFactory) || (OpenTelemetry.getMeterProvider() instanceof SecondMeterProviderFactory)); assertThat(OpenTelemetry.getMeterProvider()).isEqualTo(OpenTelemetry.getMeterProvider()); } finally { serviceFile.delete(); } }
@Test void testMeterSystemProperty() throws IOException { File serviceFile = createService( MeterProviderFactory.class, FirstMeterProviderFactory.class, SecondMeterProviderFactory.class); System.setProperty( MeterProviderFactory.class.getName(), SecondMeterProviderFactory.class.getName()); try { assertThat(OpenTelemetry.getMeterProvider()).isInstanceOf(SecondMeterProviderFactory.class); assertThat(OpenTelemetry.getMeterProvider()).isEqualTo(OpenTelemetry.getMeterProvider()); } finally { serviceFile.delete(); } }
@Test void testMeterNotFound() { System.setProperty(MeterProviderFactory.class.getName(), "io.does.not.exists"); assertThrows(IllegalStateException.class, () -> OpenTelemetry.getMeterProvider()); }